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• NumLock is so weired in Ubuntu

  - by ???

  The NumLock and the keypad is so weired in Ubuntu. I have two computers, A is a desktop, with USB keyboard, B is a laptop, with laptop keyboard and another USB keyboard. On the desktop A, whether the NumLock is on or off, the number keys on the keypad just don't work. Also the NumLock LED is always off. The logs shown in xev: KeyPress event, serial 36, synthetic NO, window 0x6800001, root 0xb0, subw 0x0, time 9541332, (172,-12), root:(1846,452), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x6800001, root 0xb0, subw 0x0, time 9541412, (172,-12), root:(1846,452), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False And on the laptop B, I found that, when the NumLock is on, then many key combinations won't work. For example, generally Ctrl-A is used to select all, but it won't work when NumLock is on. The logs shown in xev: (no log when pressed Fn+NumLock on the laptop keyboard) Logs when pressed the NumLock on the USB keyboard: (Switch On) KeyPress event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187595, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False PropertyNotify event, serial 40, synthetic NO, window 0xb600001, atom 0x1b8 (XKLAVIER_STATE), time 22187601, state PropertyNewValue KeyRelease event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187723, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False (Switch Off) KeyPress event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187899, (102,107), root:(1198,133), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False PropertyNotify event, serial 40, synthetic NO, window 0xb600001, atom 0x1b8 (XKLAVIER_STATE), time 22187904, state PropertyNewValue KeyRelease event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22188003, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False

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• How to set a static route for an external IP address

  - by HorusKol

  Further to my earlier question about bridging different subnets - I now need to route requests for one particular IP address differently to all other traffic. I have the following routing in my iptables on our router: # Allow established connections, and those !not! coming from the public interface # eth0 = public interface # eth1 = private interface #1 (10.1.1.0/24) # eth2 = private interface #2 (129.2.2.0/25) iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -m state --state NEW ! -i eth0 -j ACCEPT iptables -A FORWARD -i eth0 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i eth0 -o eth2 -m state --state ESTABLISHED,RELATED -j ACCEPT # Allow outgoing connections from the private interfaces iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT # Allow the two private connections to talk to each other iptables -A FORWARD -i eth1 -o eth2 -j ACCEPT iptables -A FORWARD -i eth2 -o eth1 -j ACCEPT # Masquerade (NAT) iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # Don't forward any other traffic from the public to the private iptables -A FORWARD -i eth0 -o eth1 -j REJECT iptables -A FORWARD -i eth0 -o eth2 -j REJECT This configuration means that users will be forwarded through a modem/router with a public address - this is all well and good for most purposes, and in the main it doesn't matter that all computers are hidden behind the one public IP. However, some users need to be able to access a proxy at 192.111.222.111:8080 - and the proxy needs to identify this traffic as coming through a gateway at 129.2.2.126 - it won't respond otherwise. I tried adding a static route on our local gateway with: route add -host 192.111.222.111 gw 129.2.2.126 dev eth2 I can successfully ping 192.111.222.111 from the router. When I trace the route, it lists the 129.2.2.126 gateway, but I just get * on each of the following hops (I think this makes sense since this is just a web-proxy and requires authentication). When I try to ping this address from a host on the 129.2.2.0/25 network it fails. Should I do this in the iptables chain instead? How would I configure this routing?

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• How to make NumLock behavior just like in Windows?

  - by ???

  The NumLock and the keypad is so weired in Ubuntu. I have two computers, A is a desktop, with USB keyboard, B is a laptop, with laptop keyboard and another USB keyboard. On the desktop A, whether the NumLock is on or off, the number keys on the keypad just don't work. Also the NumLock LED is always off. The logs shown in xev: KeyPress event, serial 36, synthetic NO, window 0x6800001, root 0xb0, subw 0x0, time 9541332, (172,-12), root:(1846,452), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x6800001, root 0xb0, subw 0x0, time 9541412, (172,-12), root:(1846,452), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False And on the laptop B, I found that, when the NumLock is on, then many key combinations won't work. For example, generally Ctrl-A is used to select all, but it won't work when NumLock is on. The logs shown in xev: (no log when pressed Fn+NumLock on the laptop keyboard) Logs when pressed the NumLock on the USB keyboard: (Switch On) KeyPress event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187595, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False PropertyNotify event, serial 40, synthetic NO, window 0xb600001, atom 0x1b8 (XKLAVIER_STATE), time 22187601, state PropertyNewValue KeyRelease event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187723, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False (Switch Off) KeyPress event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187899, (102,107), root:(1198,133), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False PropertyNotify event, serial 40, synthetic NO, window 0xb600001, atom 0x1b8 (XKLAVIER_STATE), time 22187904, state PropertyNewValue KeyRelease event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22188003, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False

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• Problems creating a functioning table

  - by Hoser

  This is a pretty simple SQL query I would assume, but I'm having problems getting it to work. if (object_id('#InfoTable')is not null) Begin Drop Table #InfoTable End create table #InfoTable (NameOfObject varchar(50), NameOfCounter varchar(50), SampledValue float(30), DayStamp datetime) insert into #InfoTable(NameOfObject, NameOfCounter, SampledValue, DayStamp) select vPerformanceRule.ObjectName AS NameOfObject, vPerformanceRule.CounterName AS NameOfCounter, Perf.vPerfRaw.SampleValue AS SampledValue, Perf.vPerfHourly.DateTime AS DayStamp from vPerformanceRule, vPerformanceRuleInstance, Perf.vPerfHourly, Perf.vPerfRaw where (ObjectName like 'Logical Disk' and CounterName like '% Free Space' AND SampleValue > 95 AND SampleValue < 100) order by DayStamp desc select NameOfObject, NameOfCounter, SampledValue, DayStamp from #InfoTable Drop Table #InfoTable I've tried various other forms of syntax, but no matter what I do, I get these error messages. Msg 207, Level 16, State 1, Line 10 Invalid column name 'NameOfObject'. Msg 207, Level 16, State 1, Line 10 Invalid column name 'NameOfCounter'. Msg 207, Level 16, State 1, Line 10 Invalid column name 'SampledValue'. Msg 207, Level 16, State 1, Line 10 Invalid column name 'DayStamp'. Msg 207, Level 16, State 1, Line 22 Invalid column name 'NameOfObject'. Msg 207, Level 16, State 1, Line 22 Invalid column name 'NameOfCounter'. Msg 207, Level 16, State 1, Line 22 Invalid column name 'SampledValue'. Msg 207, Level 16, State 1, Line 22 Invalid column name 'DayStamp'. Line 10 is the first 'insert into' line, and line 22 is the second select line. Any ideas?

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• SNMP query - operation not permitted

  - by jperovic

  I am working on API that reads a lot of data via SNMP (routes, interfaces, QoS policies, etc...). Lately, I have experienced a random error stating: Operation not permitted Now, I use SNMP4J as core library and cannot really pinpoint the source of error. Some Stackoverflow questions have suggested OS being unable to open sufficient number of file handles but increasing that parameter did not help much. The strange thing is that error occurs only when iptables is up and running. Could it be that firewall is blocking some traffic? I have tried writing JUnit test that mimicked application's logic but no errors were fired... Any help would be appreciated! Thanks! IPTABLES *nat :PREROUTING ACCEPT [2:96] :POSTROUTING ACCEPT [68:4218] :OUTPUT ACCEPT [68:4218] # route redirect za SNMP Trap i syslog -A PREROUTING -i eth0 -p udp -m udp --dport 514 -j REDIRECT --to-ports 33514 -A PREROUTING -i eth0 -p udp -m udp --dport 162 -j REDIRECT --to-ports 33162 COMMIT *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT ..... # SNMP -A INPUT -p udp -m state --state NEW -m udp --dport 161 -j ACCEPT # SNMP trap -A INPUT -p udp -m state --state NEW -m udp --dport 162 -j ACCEPT -A INPUT -p udp -m state --state NEW -m udp --dport 33162 -j ACCEPT ..... -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -j REJECT --reject-with icmp-host-prohibited COMMIT

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• Linux - Only first virtual interface can ping external gateway

  - by husvar

  I created 3 virtual interfaces with different mac addresses all linked to the same physical interface. I see that they successfully arp for the gw and they can ping (the request is coming in the packet capture in wireshark). However the ping utility does not count the responses. Does anyone knows the issue? I am running Ubuntu 14.04 in a VmWare. root@ubuntu:~# ip link sh 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 00:0c:29:bc:fc:8b brd ff:ff:ff:ff:ff:ff root@ubuntu:~# ip addr sh 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:bc:fc:8b brd ff:ff:ff:ff:ff:ff inet6 fe80::20c:29ff:febc:fc8b/64 scope link valid_lft forever preferred_lft forever root@ubuntu:~# ip route sh root@ubuntu:~# ip link add link eth0 eth0.1 addr 00:00:00:00:00:11 type macvlan root@ubuntu:~# ip link add link eth0 eth0.2 addr 00:00:00:00:00:22 type macvlan root@ubuntu:~# ip link add link eth0 eth0.3 addr 00:00:00:00:00:33 type macvlan root@ubuntu:~# ip -4 link sh 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 00:0c:29:bc:fc:8b brd ff:ff:ff:ff:ff:ff 18: eth0.1@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default link/ether 00:00:00:00:00:11 brd ff:ff:ff:ff:ff:ff 19: eth0.2@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default link/ether 00:00:00:00:00:22 brd ff:ff:ff:ff:ff:ff 20: eth0.3@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default link/ether 00:00:00:00:00:33 brd ff:ff:ff:ff:ff:ff root@ubuntu:~# ip -4 addr sh 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever root@ubuntu:~# ip -4 route sh root@ubuntu:~# dhclient -v eth0.1 Internet Systems Consortium DHCP Client 4.2.4 Copyright 2004-2012 Internet Systems Consortium. All rights reserved. For info, please visit https://www.isc.org/software/dhcp/ Listening on LPF/eth0.1/00:00:00:00:00:11 Sending on LPF/eth0.1/00:00:00:00:00:11 Sending on Socket/fallback DHCPDISCOVER on eth0.1 to 255.255.255.255 port 67 interval 3 (xid=0x568eac05) DHCPREQUEST of 192.168.1.145 on eth0.1 to 255.255.255.255 port 67 (xid=0x568eac05) DHCPOFFER of 192.168.1.145 from 192.168.1.254 DHCPACK of 192.168.1.145 from 192.168.1.254 bound to 192.168.1.145 -- renewal in 1473 seconds. root@ubuntu:~# dhclient -v eth0.2 Internet Systems Consortium DHCP Client 4.2.4 Copyright 2004-2012 Internet Systems Consortium. All rights reserved. For info, please visit https://www.isc.org/software/dhcp/ Listening on LPF/eth0.2/00:00:00:00:00:22 Sending on LPF/eth0.2/00:00:00:00:00:22 Sending on Socket/fallback DHCPDISCOVER on eth0.2 to 255.255.255.255 port 67 interval 3 (xid=0x21e3114e) DHCPREQUEST of 192.168.1.146 on eth0.2 to 255.255.255.255 port 67 (xid=0x21e3114e) DHCPOFFER of 192.168.1.146 from 192.168.1.254 DHCPACK of 192.168.1.146 from 192.168.1.254 bound to 192.168.1.146 -- renewal in 1366 seconds. root@ubuntu:~# dhclient -v eth0.3 Internet Systems Consortium DHCP Client 4.2.4 Copyright 2004-2012 Internet Systems Consortium. All rights reserved. For info, please visit https://www.isc.org/software/dhcp/ Listening on LPF/eth0.3/00:00:00:00:00:33 Sending on LPF/eth0.3/00:00:00:00:00:33 Sending on Socket/fallback DHCPDISCOVER on eth0.3 to 255.255.255.255 port 67 interval 3 (xid=0x11dc5f03) DHCPREQUEST of 192.168.1.147 on eth0.3 to 255.255.255.255 port 67 (xid=0x11dc5f03) DHCPOFFER of 192.168.1.147 from 192.168.1.254 DHCPACK of 192.168.1.147 from 192.168.1.254 bound to 192.168.1.147 -- renewal in 1657 seconds. root@ubuntu:~# ip -4 link sh 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 00:0c:29:bc:fc:8b brd ff:ff:ff:ff:ff:ff 18: eth0.1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN mode DEFAULT group default link/ether 00:00:00:00:00:11 brd ff:ff:ff:ff:ff:ff 19: eth0.2@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN mode DEFAULT group default link/ether 00:00:00:00:00:22 brd ff:ff:ff:ff:ff:ff 20: eth0.3@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN mode DEFAULT group default link/ether 00:00:00:00:00:33 brd ff:ff:ff:ff:ff:ff root@ubuntu:~# ip -4 addr sh 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 18: eth0.1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default inet 192.168.1.145/24 brd 192.168.1.255 scope global eth0.1 valid_lft forever preferred_lft forever 19: eth0.2@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default inet 192.168.1.146/24 brd 192.168.1.255 scope global eth0.2 valid_lft forever preferred_lft forever 20: eth0.3@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default inet 192.168.1.147/24 brd 192.168.1.255 scope global eth0.3 valid_lft forever preferred_lft forever root@ubuntu:~# ip -4 route sh default via 192.168.1.254 dev eth0.1 192.168.1.0/24 dev eth0.1 proto kernel scope link src 192.168.1.145 192.168.1.0/24 dev eth0.2 proto kernel scope link src 192.168.1.146 192.168.1.0/24 dev eth0.3 proto kernel scope link src 192.168.1.147 root@ubuntu:~# arping -c 5 -I eth0.1 192.168.1.254 ARPING 192.168.1.254 from 192.168.1.145 eth0.1 Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 6.936ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 2.986ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 0.654ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 5.137ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 2.426ms Sent 5 probes (1 broadcast(s)) Received 5 response(s) root@ubuntu:~# arping -c 5 -I eth0.2 192.168.1.254 ARPING 192.168.1.254 from 192.168.1.146 eth0.2 Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 5.665ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 3.753ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 16.500ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 3.287ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 32.438ms Sent 5 probes (1 broadcast(s)) Received 5 response(s) root@ubuntu:~# arping -c 5 -I eth0.3 192.168.1.254 ARPING 192.168.1.254 from 192.168.1.147 eth0.3 Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 4.422ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 2.429ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 2.321ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 40.423ms Unicast reply from 192.168.1.254 [58:98:35:57:a0:70] 2.268ms Sent 5 probes (1 broadcast(s)) Received 5 response(s) root@ubuntu:~# tcpdump -n -i eth0.1 -v & [1] 5317 root@ubuntu:~# ping -c5 -q -I eth0.1 192.168.1.254 PING 192.168.1.254 (192.168.1.254) from 192.168.1.145 eth0.1: 56(84) bytes of data. tcpdump: listening on eth0.1, link-type EN10MB (Ethernet), capture size 65535 bytes 13:18:37.612558 IP (tos 0x0, ttl 64, id 2595, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.145 > 192.168.1.254: ICMP echo request, id 5318, seq 2, length 64 13:18:37.618864 IP (tos 0x68, ttl 64, id 14493, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.145: ICMP echo reply, id 5318, seq 2, length 64 13:18:37.743650 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 192.168.1.87 tell 192.168.1.86, length 46 13:18:38.134997 IP (tos 0x0, ttl 128, id 23547, offset 0, flags [none], proto UDP (17), length 229) 192.168.1.86.138 > 192.168.1.255.138: NBT UDP PACKET(138) 13:18:38.614580 IP (tos 0x0, ttl 64, id 2596, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.145 > 192.168.1.254: ICMP echo request, id 5318, seq 3, length 64 13:18:38.793479 IP (tos 0x68, ttl 64, id 14495, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.145: ICMP echo reply, id 5318, seq 3, length 64 13:18:39.151282 IP6 (class 0x68, hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::5a98:35ff:fe57:e070 > ff02::1:ff6b:e9b4: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2001:818:d812:da00:8ae3:abff:fe6b:e9b4 source link-address option (1), length 8 (1): 58:98:35:57:a0:70 13:18:39.615612 IP (tos 0x0, ttl 64, id 2597, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.145 > 192.168.1.254: ICMP echo request, id 5318, seq 4, length 64 13:18:39.746981 IP (tos 0x68, ttl 64, id 14496, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.145: ICMP echo reply, id 5318, seq 4, length 64 --- 192.168.1.254 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4008ms rtt min/avg/max/mdev = 2.793/67.810/178.934/73.108 ms root@ubuntu:~# killall tcpdump >> /dev/null 2>&1 9 packets captured 12 packets received by filter 0 packets dropped by kernel [1]+ Done tcpdump -n -i eth0.1 -v root@ubuntu:~# tcpdump -n -i eth0.2 -v & [1] 5320 root@ubuntu:~# ping -c5 -q -I eth0.2 192.168.1.254 PING 192.168.1.254 (192.168.1.254) from 192.168.1.146 eth0.2: 56(84) bytes of data. tcpdump: listening on eth0.2, link-type EN10MB (Ethernet), capture size 65535 bytes 13:18:41.536874 ARP, Ethernet (len 6), IPv4 (len 4), Reply 192.168.1.254 is-at 58:98:35:57:a0:70, length 46 13:18:41.536933 IP (tos 0x0, ttl 64, id 2599, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.146 > 192.168.1.254: ICMP echo request, id 5321, seq 1, length 64 13:18:41.539255 IP (tos 0x68, ttl 64, id 14507, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.146: ICMP echo reply, id 5321, seq 1, length 64 13:18:42.127715 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 192.168.1.87 tell 192.168.1.86, length 46 13:18:42.511725 IP (tos 0x0, ttl 64, id 2600, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.146 > 192.168.1.254: ICMP echo request, id 5321, seq 2, length 64 13:18:42.514385 IP (tos 0x68, ttl 64, id 14527, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.146: ICMP echo reply, id 5321, seq 2, length 64 13:18:42.743856 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 192.168.1.87 tell 192.168.1.86, length 46 13:18:43.511727 IP (tos 0x0, ttl 64, id 2601, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.146 > 192.168.1.254: ICMP echo request, id 5321, seq 3, length 64 13:18:43.513768 IP (tos 0x68, ttl 64, id 14528, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.146: ICMP echo reply, id 5321, seq 3, length 64 13:18:43.637598 IP (tos 0x0, ttl 128, id 23551, offset 0, flags [none], proto UDP (17), length 225) 192.168.1.86.17500 > 255.255.255.255.17500: UDP, length 197 13:18:43.641185 IP (tos 0x0, ttl 128, id 23552, offset 0, flags [none], proto UDP (17), length 225) 192.168.1.86.17500 > 192.168.1.255.17500: UDP, length 197 13:18:43.641201 IP (tos 0x0, ttl 128, id 23553, offset 0, flags [none], proto UDP (17), length 225) 192.168.1.86.17500 > 255.255.255.255.17500: UDP, length 197 13:18:43.743890 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 192.168.1.87 tell 192.168.1.86, length 46 13:18:44.510758 IP (tos 0x0, ttl 64, id 2602, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.146 > 192.168.1.254: ICMP echo request, id 5321, seq 4, length 64 13:18:44.512892 IP (tos 0x68, ttl 64, id 14538, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.146: ICMP echo reply, id 5321, seq 4, length 64 13:18:45.510794 IP (tos 0x0, ttl 64, id 2603, offset 0, flags [DF], proto ICMP (1), length 84) 192.168.1.146 > 192.168.1.254: ICMP echo request, id 5321, seq 5, length 64 13:18:45.519701 IP (tos 0x68, ttl 64, id 14539, offset 0, flags [none], proto ICMP (1), length 84) 192.168.1.254 > 192.168.1.146: ICMP echo reply, id 5321, seq 5, length 64 13:18:49.287554 IP6 (class 0x68, hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::5a98:35ff:fe57:e070 > ff02::1:ff6b:e9b4: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2001:818:d812:da00:8ae3:abff:fe6b:e9b4 source link-address option (1), length 8 (1): 58:98:35:57:a0:70 13:18:50.013463 IP (tos 0x0, ttl 255, id 50737, offset 0, flags [DF], proto UDP (17), length 73) 192.168.1.146.5353 > 224.0.0.251.5353: 0 [2q] PTR (QM)? _ipps._tcp.local. PTR (QM)? _ipp._tcp.local. (45) 13:18:50.218874 IP6 (class 0x68, hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::5a98:35ff:fe57:e070 > ff02::1:ff6b:e9b4: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2001:818:d812:da00:8ae3:abff:fe6b:e9b4 source link-address option (1), length 8 (1): 58:98:35:57:a0:70 13:18:51.129961 IP6 (class 0x68, hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::5a98:35ff:fe57:e070 > ff02::1:ff6b:e9b4: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2001:818:d812:da00:8ae3:abff:fe6b:e9b4 source link-address option (1), length 8 (1): 58:98:35:57:a0:70 13:18:52.197074 IP6 (hlim 255, next-header UDP (17) payload length: 53) 2001:818:d812:da00:200:ff:fe00:22.5353 > ff02::fb.5353: [udp sum ok] 0 [2q] PTR (QM)? _ipps._tcp.local. PTR (QM)? _ipp._tcp.local. (45) 13:18:54.128240 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 192.168.1.87 tell 192.168.1.86, length 46 --- 192.168.1.254 ping statistics --- 5 packets transmitted, 0 received, 100% packet loss, time 4000ms root@ubuntu:~# killall tcpdump >> /dev/null 2>&1 13:18:54.657731 IP6 (class 0x68, hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::5a98:35ff:fe57:e070 > ff02::1:ff6b:e9b4: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2001:818:d812:da00:8ae3:abff:fe6b:e9b4 source link-address option (1), length 8 (1): 58:98:35:57:a0:70 13:18:54.743174 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 192.168.1.87 tell 192.168.1.86, length 46 25 packets captured 26 packets received by filter 0 packets dropped by kernel [1]+ Done tcpdump -n -i eth0.2 -v root@ubuntu:~# tcpdump -n -i eth0.3 icmp & [1] 5324 root@ubuntu:~# ping -c5 -q -I eth0.3 192.168.1.254 PING 192.168.1.254 (192.168.1.254) from 192.168.1.147 eth0.3: 56(84) bytes of data. tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0.3, link-type EN10MB (Ethernet), capture size 65535 bytes 13:18:56.373434 IP 192.168.1.147 > 192.168.1.254: ICMP echo request, id 5325, seq 1, length 64 13:18:57.372116 IP 192.168.1.147 > 192.168.1.254: ICMP echo request, id 5325, seq 2, length 64 13:18:57.381263 IP 192.168.1.254 > 192.168.1.147: ICMP echo reply, id 5325, seq 2, length 64 13:18:58.371141 IP 192.168.1.147 > 192.168.1.254: ICMP echo request, id 5325, seq 3, length 64 13:18:58.373275 IP 192.168.1.254 > 192.168.1.147: ICMP echo reply, id 5325, seq 3, length 64 13:18:59.371165 IP 192.168.1.147 > 192.168.1.254: ICMP echo request, id 5325, seq 4, length 64 13:18:59.373259 IP 192.168.1.254 > 192.168.1.147: ICMP echo reply, id 5325, seq 4, length 64 13:19:00.371211 IP 192.168.1.147 > 192.168.1.254: ICMP echo request, id 5325, seq 5, length 64 13:19:00.373278 IP 192.168.1.254 > 192.168.1.147: ICMP echo reply, id 5325, seq 5, length 64 --- 192.168.1.254 ping statistics --- 5 packets transmitted, 1 received, 80% packet loss, time 4001ms rtt min/avg/max/mdev = 13.666/13.666/13.666/0.000 ms root@ubuntu:~# killall tcpdump >> /dev/null 2>&1 9 packets captured 10 packets received by filter 0 packets dropped by kernel [1]+ Done tcpdump -n -i eth0.3 icmp root@ubuntu:~# arp -n Address HWtype HWaddress Flags Mask Iface 192.168.1.254 ether 58:98:35:57:a0:70 C eth0.1 192.168.1.254 ether 58:98:35:57:a0:70 C eth0.2 192.168.1.254 ether 58:98:35:57:a0:70 C eth0.3

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• Using Stub Objects

  - by user9154181

  Having told the long and winding tale of where stub objects came from and how we use them to build Solaris, I'd like to focus now on the the nuts and bolts of building and using them. The following new features were added to the Solaris link-editor (ld) to support the production and use of stub objects: -z stub This new command line option informs ld that it is to build a stub object rather than a normal object. In this mode, it accepts the same command line arguments as usual, but will quietly ignore any objects and sharable object dependencies. STUB_OBJECT Mapfile Directive In order to build a stub version of an object, its mapfile must specify the STUB_OBJECT directive. When producing a non-stub object, the presence of STUB_OBJECT causes the link-editor to perform extra validation to ensure that the stub and non-stub objects will be compatible. ASSERT Mapfile Directive All data symbols exported from the object must have an ASSERT symbol directive in the mapfile that declares them as data and supplies the size, binding, bss attributes, and symbol aliasing details. When building the stub objects, the information in these ASSERT directives is used to create the data symbols. When building the real object, these ASSERT directives will ensure that the real object matches the linking interface presented by the stub. Although ASSERT was added to the link-editor in order to support stub objects, they are a general purpose feature that can be used independently of stub objects. For instance you might choose to use an ASSERT directive if you have a symbol that must have a specific address in order for the object to operate properly and you want to automatically ensure that this will always be the case. The material presented here is derived from a document I originally wrote during the development effort, which had the dual goals of providing supplemental materials for the stub object PSARC case, and as a set of edits that were eventually applied to the Oracle Solaris Linker and Libraries Manual (LLM). The Solaris 11 LLM contains this information in a more polished form. Stub Objects A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be used at runtime. However, an application can be built against a stub object, where the stub object provides the real object name to be used at runtime, and then use the real object at runtime. When building a stub object, the link-editor ignores any object or library files specified on the command line, and these files need not exist in order to build a stub. Since the compilation step can be omitted, and because the link-editor has relatively little work to do, stub objects can be built very quickly. Stub objects can be used to solve a variety of build problems: Speed Modern machines, using a version of make with the ability to parallelize operations, are capable of compiling and linking many objects simultaneously, and doing so offers significant speedups. However, it is typical that a given object will depend on other objects, and that there will be a core set of objects that nearly everything else depends on. It is necessary to impose an ordering that builds each object before any other object that requires it. This ordering creates bottlenecks that reduce the amount of parallelization that is possible and limits the overall speed at which the code can be built. Complexity/Correctness In a large body of code, there can be a large number of dependencies between the various objects. The makefiles or other build descriptions for these objects can become very complex and difficult to understand or maintain. The dependencies can change as the system evolves. This can cause a given set of makefiles to become slightly incorrect over time, leading to race conditions and mysterious rare build failures. Dependency Cycles It might be desirable to organize code as cooperating shared objects, each of which draw on the resources provided by the other. Such cycles cannot be supported in an environment where objects must be built before the objects that use them, even though the runtime linker is fully capable of loading and using such objects if they could be built. Stub shared objects offer an alternative method for building code that sidesteps the above issues. Stub objects can be quickly built for all the shared objects produced by the build. Then, all the real shared objects and executables can be built in parallel, in any order, using the stub objects to stand in for the real objects at link-time. Afterwards, the executables and real shared objects are kept, and the stub shared objects are discarded. Stub objects are built from a mapfile, which must satisfy the following requirements. The mapfile must specify the STUB_OBJECT directive. This directive informs the link-editor that the object can be built as a stub object, and as such causes the link-editor to perform validation and sanity checking intended to guarantee that an object and its stub will always provide identical linking interfaces. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data exported from the object must have an ASSERT symbol attribute in the mapfile to specify the symbol type, size, and bss attributes. In the case where there are multiple symbols that reference the same data, the ASSERT for one of these symbols must specify the TYPE and SIZE attributes, while the others must use the ALIAS attribute to reference this primary symbol. Given such a mapfile, the stub and real versions of the shared object can be built using the same command line for each, adding the '-z stub' option to the link for the stub object, and omiting the option from the link for the real object. To demonstrate these ideas, the following code implements a shared object named idx5, which exports data from a 5 element array of integers, with each element initialized to contain its zero-based array index. This data is available as a global array, via an alternative alias data symbol with weak binding, and via a functional interface. % cat idx5.c int _idx5[5] = { 0, 1, 2, 3, 4 }; #pragma weak idx5 = _idx5 int idx5_func(int index) { if ((index 4)) return (-1); return (_idx5[index]); } A mapfile is required to describe the interface provided by this shared object. % cat mapfile $mapfile_version 2 STUB_OBJECT; SYMBOL_SCOPE { _idx5 { ASSERT { TYPE=data; SIZE=4[5] }; }; idx5 { ASSERT { BINDING=weak; ALIAS=_idx5 }; }; idx5_func; local: *; }; The following main program is used to print all the index values available from the idx5 shared object. % cat main.c #include <stdio.h> extern int _idx5[5], idx5[5], idx5_func(int); int main(int argc, char **argv) { int i; for (i = 0; i The following commands create a stub version of this shared object in a subdirectory named stublib. elfdump is used to verify that the resulting object is a stub. The command used to build the stub differs from that of the real object only in the addition of the -z stub option, and the use of a different output file name. This demonstrates the ease with which stub generation can be added to an existing makefile. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o stublib/libidx5.so.1 -zstub % ln -s libidx5.so.1 stublib/libidx5.so % elfdump -d stublib/libidx5.so | grep STUB [11] FLAGS_1 0x4000000 [ STUB ] The main program can now be built, using the stub object to stand in for the real shared object, and setting a runpath that will find the real object at runtime. However, as we have not yet built the real object, this program cannot yet be run. Attempts to cause the system to load the stub object are rejected, as the runtime linker knows that stub objects lack the actual code and data found in the real object, and cannot execute. % cc main.c -L stublib -R '$ORIGIN/lib' -lidx5 -lc % ./a.out ld.so.1: a.out: fatal: libidx5.so.1: open failed: No such file or directory Killed % LD_PRELOAD=stublib/libidx5.so.1 ./a.out ld.so.1: a.out: fatal: stublib/libidx5.so.1: stub shared object cannot be used at runtime Killed We build the real object using the same command as we used to build the stub, omitting the -z stub option, and writing the results to a different file. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o lib/libidx5.so.1 Once the real object has been built in the lib subdirectory, the program can be run. % ./a.out [0] 0 0 0 [1] 1 1 1 [2] 2 2 2 [3] 3 3 3 [4] 4 4 4 Mapfile Changes The version 2 mapfile syntax was extended in a number of places to accommodate stub objects. Conditional Input The version 2 mapfile syntax has the ability conditionalize mapfile input using the $if control directive. As you might imagine, these directives are used frequently with ASSERT directives for data, because a given data symbol will frequently have a different size in 32 or 64-bit code, or on differing hardware such as x86 versus sparc. The link-editor maintains an internal table of names that can be used in the logical expressions evaluated by $if and $elif. At startup, this table is initialized with items that describe the class of object (_ELF32 or _ELF64) and the type of the target machine (_sparc or _x86). We found that there were a small number of cases in the Solaris code base in which we needed to know what kind of object we were producing, so we added the following new predefined items in order to address that need: NameMeaning ...... _ET_DYNshared object _ET_EXECexecutable object _ET_RELrelocatable object ...... STUB_OBJECT Directive The new STUB_OBJECT directive informs the link-editor that the object described by the mapfile can be built as a stub object. STUB_OBJECT; A stub shared object is built entirely from the information in the mapfiles supplied on the command line. When the -z stub option is specified to build a stub object, the presence of the STUB_OBJECT directive in a mapfile is required, and the link-editor uses the information in symbol ASSERT attributes to create global symbols that match those of the real object. When the real object is built, the presence of STUB_OBJECT causes the link-editor to verify that the mapfiles accurately describe the real object interface, and that a stub object built from them will provide the same linking interface as the real object it represents. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data in the object is required to have an ASSERT attribute that specifies the symbol type and size. If the ASSERT BIND attribute is not present, the link-editor provides a default assertion that the symbol must be GLOBAL. If the ASSERT SH_ATTR attribute is not present, or does not specify that the section is one of BITS or NOBITS, the link-editor provides a default assertion that the associated section is BITS. All data symbols that describe the same address and size are required to have ASSERT ALIAS attributes specified in the mapfile. If aliased symbols are discovered that do not have an ASSERT ALIAS specified, the link fails and no object is produced. These rules ensure that the mapfiles contain a description of the real shared object's linking interface that is sufficient to produce a stub object with a completely compatible linking interface. SYMBOL_SCOPE/SYMBOL_VERSION ASSERT Attribute The SYMBOL_SCOPE and SYMBOL_VERSION mapfile directives were extended with a symbol attribute named ASSERT. The syntax for the ASSERT attribute is as follows: ASSERT { ALIAS = symbol_name; BINDING = symbol_binding; TYPE = symbol_type; SH_ATTR = section_attributes; SIZE = size_value; SIZE = size_value[count]; }; The ASSERT attribute is used to specify the expected characteristics of the symbol. The link-editor compares the symbol characteristics that result from the link to those given by ASSERT attributes. If the real and asserted attributes do not agree, a fatal error is issued and the output object is not created. In normal use, the link editor evaluates the ASSERT attribute when present, but does not require them, or provide default values for them. The presence of the STUB_OBJECT directive in a mapfile alters the interpretation of ASSERT to require them under some circumstances, and to supply default assertions if explicit ones are not present. See the definition of the STUB_OBJECT Directive for the details. When the -z stub command line option is specified to build a stub object, the information provided by ASSERT attributes is used to define the attributes of the global symbols provided by the object. ASSERT accepts the following: ALIAS Name of a previously defined symbol that this symbol is an alias for. An alias symbol has the same type, value, and size as the main symbol. The ALIAS attribute is mutually exclusive to the TYPE, SIZE, and SH_ATTR attributes, and cannot be used with them. When ALIAS is specified, the type, size, and section attributes are obtained from the alias symbol. BIND Specifies an ELF symbol binding, which can be any of the STB_ constants defined in <sys/elf.h>, with the STB_ prefix removed (e.g. GLOBAL, WEAK). TYPE Specifies an ELF symbol type, which can be any of the STT_ constants defined in <sys/elf.h>, with the STT_ prefix removed (e.g. OBJECT, COMMON, FUNC). In addition, for compatibility with other mapfile usage, FUNCTION and DATA can be specified, for STT_FUNC and STT_OBJECT, respectively. TYPE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SH_ATTR Specifies attributes of the section associated with the symbol. The section_attributes that can be specified are given in the following table: Section AttributeMeaning BITSSection is not of type SHT_NOBITS NOBITSSection is of type SHT_NOBITS SH_ATTR is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SIZE Specifies the expected symbol size. SIZE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. The syntax for the size_value argument is as described in the discussion of the SIZE attribute below. SIZE The SIZE symbol attribute existed before support for stub objects was introduced. It is used to set the size attribute of a given symbol. This attribute results in the creation of a symbol definition. Prior to the introduction of the ASSERT SIZE attribute, the value of a SIZE attribute was always numeric. While attempting to apply ASSERT SIZE to the objects in the Solaris ON consolidation, I found that many data symbols have a size based on the natural machine wordsize for the class of object being produced. Variables declared as long, or as a pointer, will be 4 bytes in size in a 32-bit object, and 8 bytes in a 64-bit object. Initially, I employed the conditional $if directive to handle these cases as follows: $if _ELF32 foo { ASSERT { TYPE=data; SIZE=4 } }; bar { ASSERT { TYPE=data; SIZE=20 } }; $elif _ELF64 foo { ASSERT { TYPE=data; SIZE=8 } }; bar { ASSERT { TYPE=data; SIZE=40 } }; $else $error UNKNOWN ELFCLASS $endif I found that the situation occurs frequently enough that this is cumbersome. To simplify this case, I introduced the idea of the addrsize symbolic name, and of a repeat count, which together make it simple to specify machine word scalar or array symbols. Both the SIZE, and ASSERT SIZE attributes support this syntax: The size_value argument can be a numeric value, or it can be the symbolic name addrsize. addrsize represents the size of a machine word capable of holding a memory address. The link-editor substitutes the value 4 for addrsize when building 32-bit objects, and the value 8 when building 64-bit objects. addrsize is useful for representing the size of pointer variables and C variables of type long, as it automatically adjusts for 32 and 64-bit objects without requiring the use of conditional input. The size_value argument can be optionally suffixed with a count value, enclosed in square brackets. If count is present, size_value and count are multiplied together to obtain the final size value. Using this feature, the example above can be written more naturally as: foo { ASSERT { TYPE=data; SIZE=addrsize } }; bar { ASSERT { TYPE=data; SIZE=addrsize[5] } }; Exported Global Data Is Still A Bad Idea As you can see, the additional plumbing added to the Solaris link-editor to support stub objects is minimal. Furthermore, about 90% of that plumbing is dedicated to handling global data. We have long advised against global data exported from shared objects. There are many ways in which global data does not fit well with dynamic linking. Stub objects simply provide one more reason to avoid this practice. It is always better to export all data via a functional interface. You should always hide your data, and make it available to your users via a function that they can call to acquire the address of the data item. However, If you do have to support global data for a stub, perhaps because you are working with an already existing object, it is still easilily done, as shown above. Oracle does not like us to discuss hypothetical new features that don't exist in shipping product, so I'll end this section with a speculation. It might be possible to do more in this area to ease the difficulty of dealing with objects that have global data that the users of the library don't need. Perhaps someday... Conclusions It is easy to create stub objects for most objects. If your library only exports function symbols, all you have to do to build a faithful stub object is to add STUB_OBJECT; and then to use the same link command you're currently using, with the addition of the -z stub option. Happy Stubbing!

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• Generics with constraints hierarchy

  - by devoured elysium

  I am currently facing a very disturbing problem: interface IStateSpace<Position, Value> where Position : IPosition // <-- Problem starts here where Value : IValue // <-- and here as I don't { // know how to get away this // circular dependency! // Notice how I should be // defining generics parameters // here but I can't! Value GetStateAt(Position position); void SetStateAt(Position position, State state); } As you'll down here, both IPosition, IValue and IState depend on each other. How am I supposed to get away with this? I can't think of any other design that will circumvent this circular dependency and still describes exactly what I want to do! interface IState<StateSpace, Value> where StateSpace : IStateSpace where Value : IValue { StateSpace StateSpace { get; }; Value Value { get; set; } } interface IPosition { } interface IValue<State> where State : IState { State State { get; } } Basically I have a state space IStateSpace that has states IState inside. Their position in the state space is given by an IPosition. Each state then has one (or more) values IValue. I am simplifying the hierarchy, as it's a bit more complex than described. The idea of having this hierarchy defined with generics is to allow for different implementations of the same concepts (an IStateSpace will be implemented both as a matrix as an graph, etc). Would can I get away with this? How do you generally solve this kind of problems? Which kind of designs are used in these cases? Thanks

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• How do I check if a user is authenticated with NickServ using POE::Component::IRC::State in Perl?

  - by Troy

  I'm trying to test whether a user is registered on FreeNode. nick_info() doesn't seem to return information about this, so I want to use $irc-yield(whois = $nick); and then grab the irc_whois event's reply. The problem is that I want to wait until this event is fired, so I created a global variable $whois_result and wrote a sub like this: sub whois { my $nick = $_[0]; $whois_result = 0; $irc->yield(whois => $nick); while($whois_result == 0) { } return $whois_result; } with the irc_whois handler looking like: sub on_whois { $whois_result = $_[ARG0]; print "DEBUG: irc_whois fired.\n"; } Unfortunately, the event can't fire while the loop is running so this hangs. I'm sure there's a better way to do this, but I'm not familiar enough with this kind of programming to know. Any help would be greatly appreciated.

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• verilog / systemverilog -- What is the behavior of blocking statements across two always blocks?

  - by miles.sherman

  I am wondering about the behavior of the below code. There are two always blocks, one is combinational to calculate the next_state signal, the other is sequential which will perform some logic and determine whether or not to shutdown the system. It does this by setting the shutdown_now signal high and then calling state <= next_state. My question is if the conditions become true that the shutdown_now signal is set (during clock cycle n) in a blocking manner before the state <= next_state line, will the state during clock cycle n+1 be SHUTDOWN or RUNNING? In other words, does the shutdown_now = 1'b1 line block across both state machines since the state signal is dependent on it through the next_state determination? enum {IDLE, RUNNING, SHUTDOWN} state, next_state; logic shutdown_now; // State machine (combinational) always_comb begin case (state) IDLE: next_state <= RUNNING; RUNNING: next_state <= shutdown ? SHUTDOWN : RUNNING; SHUTDOWN: next_state <= SHUTDOWN; default: next_state <= SHUTDOWN; endcase end // Sequential Behavior always_ff @ (posedge clk) begin // Some code here if (/*some condition) begin shutdown_now = 1'b0; end else begin shutdown_now = 1'b1; end state <= next_state; end

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• How can I SETF an element in a tree by an accessor?

  - by Willi Ballenthin

  We've been using Lisp in my AI course. The assignments I've received have involved searching and generating tree-like structures. For each assignment, I've ended up writing something like: (defun initial-state () (list 0 ; score nil ; children 0 ; value 0)) ; something else and building my functions around these "states", which are really just nested lists with some loosely defined structure. To make the structure more rigid, I've tried to write accessors, such as: (defun state-score ( state ) (nth 2 state)) This works for reading the value (which should be all I need to do in a nicely functional world. However, as time crunches, and I start to madly hack, sometimes I want a mutable structure). I don't seem to be able to SETF the returned ...thing (place? value? pointer?). I get an error with something like: (setf (state-score *state*) 10) Sometimes I seem to have a little more luck writing the accessor/mutator as a macro: (defmacro state-score ( state ) `(nth 2 ,state)) However I don't know why this should be a macro, so I certainly shouldn't write it as a macro (except that sometimes it works. Programming by coincidence is bad). What is an appropriate strategy to build up such structures? More importantly, where can I learn about whats going on here (what operations affect the memory in what way)?

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• Dynamic select menu Rails, Javascript HABTM

  - by Jack

  Hi, I am following a tutorial in one of Ryan Bates' Railscasts here. Basically I want a form where there are 2 drop down menus, the contents of one are dependent on the other. I have Years and Courses, where Years HABMT Courses and Courses HABTM Years. In the tutorial, the javascript is as follows: var states = new Array(); <% for state in @states -%> states.push(new Array(<%= state.country_id %>, '<%=h state.name %>', <%= state.id %>)); <% end -%> function countrySelected() { country_id = $('person_country_id').getValue(); options = $('person_state_id').options; options.length = 1; states.each(function(state) { if (state[0] == country_id) { options[options.length] = new Option(state[1], state[2]); } }); if (options.length == 1) { $('state_field').hide(); } else { $('state_field').show(); } } document.observe('dom:loaded', function() { countrySelected(); $('person_country_id').observe('change', countrySelected); }); Where I guess country has many states and state belongs to country. I think what I need to do is edit the first for statement to somehow loop through all of the courses for each year_id, but don't know how to do this. Any ideas? Thanks

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• Circular dependency with generics

  - by devoured elysium

  I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

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• HiddenField.Value is an empty string upon postback inside my custom control

  - by Matthew Cox

  I have a custom control that has a hidden field. Upon postback I want to obtain the value stored in it, but it's always an empty string. any thoughts? I am performing client-side manipulation of the hidden field values and have verified in firebug that the fields are correct before issue a post back Here is the setup: public class DualListPanel : SWebControl, INamingContainer { protected IList<DlpItem> UnassignedList { get; set; } protected IList<DlpItem> AssignedList { get; set; } private HiddenField assignedItemsField, unassignedItemsField; public DualListPanel() { CssClass = "DualListPanel"; EnableViewState = true; } #region ViewState protected override void LoadViewState(object savedState) { var state = savedState as object[]; UnassignedList = state[0] as List<DlpItem>; AssignedList = state[1] as List<DlpItem>; base.LoadViewState(state[2]); } protected override object SaveViewState() { object[] state = new object[3]; state[0] = UnassignedList; state[1] = AssignedList; state[2] = base.SaveViewState(); return state; } #endregion #region WebControl Overrides protected override void CreateChildControls() { assignedItemsField = new HiddenField(); assignedItemsField.ID = "HiddenAssignedItems"; assignedItemsField.EnableViewState = true; unassignedItemsField = new HiddenField(); unassignedItemsField.ID = "HiddenUnassignedItems"; unassignedItemsField.EnableViewState = true; Controls.Add(assignedItemsField); Controls.Add(unassignedItemsField); base.CreateChildControls(); } #endregion #region Item Lists Retrieval public string GetCommaDelimUnassignedItems() { return unassignedItemsField.Value; } public string GetCommaDelimAssignedItems() { return assignedItemsField.Value; } #endregion }

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• How to make creating viewmodels at runtime less painful

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painful. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genius since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use a DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an in-depth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• MVVM - how to make creating viewmodels at runtime less painfull

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• Legislative Alert - Payroll for North America

  - by Carolyn Cozart

  We have a Legislative Alert for our customers using PeopleSoft Payroll for North America.   The IRS has made some changes to the FUTA reporting for the tax year 2011.  The IRS requires that all employers complete the 940 Schedule A form when completing the Tax Form 940.  On the Schedule A employers must indicate every state in which you were required to pay state unemployment tax during the year (even if that state's credit reduction rate was zero).  For states with a credit reduction rate greater than zero you must enter the FUTA taxable wages paid in that state then multiply it by the credit reduction rate to report the credit reduction amount for that state.  Please go to Document ID 1371681.1 to obtain additional information on this regulation along with Oracle/PeopleSoft position on this new requirement.

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• How to make creating viewmodels at runtime less painfull

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• How to get Passive FTP Working Through an Iptables Firewall?

  - by user1133248

  I have an iptables firewall running on a Fedora Linux server that is basically being used as a firewall router and OpenVPN server. That's it. We have been using the same iptables firewall code for YEARS. I did make some changes on 21 December to re-route a mySQL port, but given what has happened I've completely backed those changes out. Sometime after those changes were made and backed out passive FTP, served from a vsftpd process, stopped working. We use a passive ftp client to FLING (that's the name of the ftp client running under Windows! :-) ) images from our remote telescopes to our server. I believe it is something in the firewall code because I can drop the firewall and the FTP file transfer (and connecting to the ftp site with Internet Explorer to see the file list) works. When I raise the iptables firewall, it stops working. Again, this is code that we'd been using for years. However, I felt that maybe there was something I missed, so we had a .bak file from 2009 that I used. Same behavior, passive ftp does not work. So, I went and rebuilt the firewall code line by line to see what line was causing the problem. Everything worked until I put the line -A FORWARD -j DROP in very near the end. Of course, if I am correct, this is the line that basically "turns on" the firewall, saying drop everything except for the exceptions I've made above. However, this line has been in the iptables code probably since 2003. So, I'm at the end of my rope, and I still can't figure out why this has stopped working. I guess I need an expert on iptables configuration. Here is the iptables code (from iptables-save) with comments. # Generated by iptables-save v1.3.8 on Thu Jan 5 18:36:25 2012 *nat # One of the things that I remain ignorant about is what these following three lines # do in both the nat tables (which we're not using on this machine) and the following # filter table. I don't know what the numbers are, but I'm ASSUMING they're port # ranges. # :PREROUTING ACCEPT [7435:551429] :POSTROUTING ACCEPT [6097:354458] :OUTPUT ACCEPT [5:451] COMMIT # Completed on Thu Jan 5 18:36:25 2012 # Generated by iptables-save v1.3.8 on Thu Jan 5 18:36:25 2012 *filter :INPUT ACCEPT [10423:1046501] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [15184:16948770] # The following line is for my OpenVPN configuration. -A INPUT -i tun+ -j ACCEPT # In researching this on the Internet I found some iptables code that was supposed to # open the needed ports up. I never needed this before this week, but since passive FTP # was no longer working, I decided to put the code in. The next three lines are part of # that code. -A INPUT -p tcp -m tcp --dport 21 -m state --state NEW,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --sport 1024:65535 --dport 20 -m state --state ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --sport 1024:65535 --dport 1024:65535 -m state --state RELATED,ESTABLISHED -j ACCEPT # Another line for the OpenVPN configuration. I don't know why the iptables-save mixed # the lines up. -A FORWARD -i tun+ -j ACCEPT # Various forwards for all our services -A FORWARD -s 65.118.148.197 -p tcp -m tcp --dport 3307 -j ACCEPT -A FORWARD -d 65.118.148.197 -p tcp -m tcp --dport 3307 -j ACCEPT -A FORWARD -s 65.118.148.197 -p tcp -m tcp --dport 3306 -j ACCEPT -A FORWARD -d 65.118.148.197 -p tcp -m tcp --dport 3306 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 21 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 21 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 20 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 20 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 7191 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 7191 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 46000:46999 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 46000:46999 -j ACCEPT -A FORWARD -s 65.118.148.0/255.255.255.0 -j ACCEPT -A FORWARD -d 65.118.148.196 -p udp -m udp --dport 53 -j ACCEPT -A FORWARD -s 65.118.148.196 -p udp -m udp --dport 53 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 53 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 53 -j ACCEPT -A FORWARD -d 65.118.148.196 -p udp -m udp --dport 25 -j ACCEPT -A FORWARD -s 65.118.148.196 -p udp -m udp --dport 25 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 42 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 42 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 25 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 25 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 80 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 80 -j ACCEPT -A FORWARD -d 65.118.148.204 -p tcp -m tcp --dport 80 -j ACCEPT -A FORWARD -s 65.118.148.204 -p tcp -m tcp --dport 80 -j ACCEPT -A FORWARD -d 65.118.148.196 -p tcp -m tcp --dport 6667 -j ACCEPT -A FORWARD -s 65.118.148.196 -p tcp -m tcp --dport 6667 -j ACCEPT -A FORWARD -s 65.96.214.242 -p tcp -m tcp --dport 22 -j ACCEPT -A FORWARD -s 192.68.148.66 -p tcp -m tcp --dport 22 -j ACCEPT -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT # "The line" that causes passive ftp to stop working. Insofar as I can tell, everything # else seems to work - ssh, telnet, mysql, httpd. -A FORWARD -j DROP -A FORWARD -p icmp -j ACCEPT # The following code is again part of my attempt to put in code that would cause passive # ftp to work. I don't know why iptables-save scattered it about like this. -A OUTPUT -p tcp -m tcp --sport 21 -m state --state ESTABLISHED -j ACCEPT -A OUTPUT -p tcp -m tcp --sport 20 --dport 1024:65535 -m state --state RELATED,ESTABLISHED -j ACCEPT -A OUTPUT -p tcp -m tcp --sport 1024:65535 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT COMMIT # Completed on Thu Jan 5 18:36:25 2012 So, with all that prelude, my basic question is: How can I get passive ftp to work behind an iptables firewall? As you can see, I've tried to get it working (again) and tried to do some research on the issue, but have come up...short. Any answers would be appreciated by both me and various variable star astronomers around the world! THANKS! -Richard "Doc" Kinne, American Assoc. of Variable Star Observers, [email protected]

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• Is the valid state domain of a program a regular language?

  - by BCS

  If you look at the call stack of a program and treat each return pointer as a token, what kind of automata is needed to build a recognizer for the valid states of the program? As a corollary, what kind of automata is needed to build a recognizer for a specific bug state? My thought is that if these form regular languages than some interesting tools could be built around that. E.g. given a set of crash/failure dumps, automatically group them and generate a recognizer to identify new instances of know bugs.

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• JavaScript: Reference a functions local scope as an object

  - by eBusiness

  When I call a function, a local scope is erected for that call. Is there any way to directly reference that scope as an object? Just like window is a reference for the global scope object. Example: function test(foo){ var bar=1 //Now, can I access the object containing foo, bar, arguments and anything //else within the local scope like this: magicIdentifier.bar } Alternately, does anyone have a complete list of what is in the global scope on top of custom variables? Background: I'm trying to get down to a way of completely shifting to global scope from within a function call, the with statement is a joke, call works a little better, but it still breaks for anything declared in function scope but not in global scope, therefore I would declare these few cases in global scope, but that requires me to know what they are. The IE function execScript makes a complete shift, but that only solves the problem for IE. Note: To anyone loading JavaScript dynamically, setTimeout(code,1) is a simple effective hack to achieve global scope, but it will not execute immediately.

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• Error 18456. State 6 "Attempting to use an NT account name with SQL Server Authentication."

  - by Aragorn

  2010-05-06 17:21:22.30 Logon Error: 18456, Severity: 14, State: 6. 2010-05-06 17:21:22.30 Logon Login failed for user . Reason: Attempting to use an NT account name with SQL Server Authentication. [CLIENT: ] The authentication mode is "Mixed". And its MS SQL Server 2008. What might be the issue? Do you think the user name was not configured properly? Is there any link available for giving the right privileges and configuring the user account? So that I can check the rights and privileges for the acc I am using... thanks

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• how to maintain a Presistent state of an app in Android?

  - by androidbase Praveen

  hi all, i am working on my App. in between i pressed the Home button on the device. my app will go to the background tasks. After that i long press the home button it will show my app as a persistent state. i.e where and what i had done in my app. But i click my app in the directory window it restarts my app. i want to do if my app is in the background tasks it will wake up else it will start. how to achieve that? Any Idea?

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• how to maintain a Home Button Presistent state of an app in Android?

  - by androidbase Praveen

  hi all, i am working on my App. in between i pressed the Home button on the device. my app will go to the background tasks. After that i long press the home button it will show my app as a persistent state. i.e where and what i had done in my app. But i click my app in the directory window it restarts my app. i want to do if my app is in the background tasks it will wake up else it will start. how to achieve that? Any Idea?

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• NHibernate FetchMode.Lazy

  - by RyanFetz

  I have an object which has a property on it that has then has collections which i would like to not load in a couple situations. 98% of the time i want those collections fetched but in the one instance i do not. Here is the code I have... Why does it not set the fetch mode on the properties collections? [DataContract(Name = "ThemingJob", Namespace = "")] [Serializable] public class ThemingJob : ServiceJob { [DataMember] public virtual Query Query { get; set; } [DataMember] public string Results { get; set; } } [DataContract(Name = "Query", Namespace = "")] [Serializable] public class Query : LookupEntity<Query>, DAC.US.Search.Models.IQueryEntity { [DataMember] public string QueryResult { get; set; } private IList<Asset> _Assets = new List<Asset>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Asset> Assets { get { return _Assets; } set { _Assets = value; } } private IList<Theme> _Themes = new List<Theme>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Theme> Themes { get { return _Themes; } set { _Themes = value; } } private IList<Affinity> _Affinity = new List<Affinity>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Affinity> Affinity { get { return _Affinity; } set { _Affinity = value; } } private IList<Word> _Words = new List<Word>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Word> Words { get { return _Words; } set { _Words = value; } } } using (global::NHibernate.ISession session = NHibernateApplication.GetCurrentSession()) { global::NHibernate.ICriteria criteria = session.CreateCriteria(typeof(ThemingJob)); global::NHibernate.ICriteria countCriteria = session.CreateCriteria(typeof(ThemingJob)); criteria.AddOrder(global::NHibernate.Criterion.Order.Desc("Id")); var qc = criteria.CreateCriteria("Query"); qc.SetFetchMode("Assets", global::NHibernate.FetchMode.Lazy); qc.SetFetchMode("Themes", global::NHibernate.FetchMode.Lazy); qc.SetFetchMode("Affinity", global::NHibernate.FetchMode.Lazy); qc.SetFetchMode("Words", global::NHibernate.FetchMode.Lazy); pageIndex = Convert.ToInt32(pageIndex) - 1; // convert to 0 based paging index criteria.SetMaxResults(pageSize); criteria.SetFirstResult(pageIndex * pageSize); countCriteria.SetProjection(global::NHibernate.Criterion.Projections.RowCount()); int totalRecords = (int)countCriteria.List()[0]; return criteria.List<ThemingJob>().ToPagedList<ThemingJob>(pageIndex, pageSize, totalRecords); }

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