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• Load balancing a Windows File Share using HA-Proxy

  - by NathanE

  After pulling my hair out over DFS I just had this weird and potentially dangerous idea come into my head whereby, just possibly, I might be able to use HA-Proxy to load balance a file share between servers. I've done some remedial packet traces and it does appear that TCP port 445 is the only thing involved in using Windows file sharing. I've always thought for many years that UDP 139, 135 etc were also involved in at least establishing the connection - but apparently not! So I setup a basic test: listen SMBTest *:445 mode tcp server Smb1 172.16.61.201:445 server Smb2 172.16.61.202:445 And you'll never guess what... it works??? (!) Now obviously there is the whole concern about synchronisation between the file servers (of course). That could easily be taken care of with a little bit of Robocopy script. And considering I only need a HA read-only file share there wouldn't be any issues with regard to file locking etc. Can anyone tell me if what I'm playing with here is fire? I really didn't think it would work at all and now I'm a little shocked. What would be the downsides? Could this be relied upon for a production environment?

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• How to find the real IP to which IPVS is routing a virtual IP

  - by Wayne Conrad

  I'm trying to find a problem server hiding behind a virtual IP (using LVS/ipvs). I've got a test program that sends requests to the virtual IP until it gets the bad response, but how can I tell to which real IP a request to the virtual IP got routed? On the box doing the virtual IP magic, here's the virtual IP configuration (for the service I care about): IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn ... TCP 10.1.0.254:5025 nq -> 10.1.0.5:5025 Route 1 0 1 -> 10.1.0.6:5025 Route 1 0 5 -> 10.1.0.7:5025 Route 1 0 2 -> 10.1.0.9:5025 Local 1 0 3 -> 10.1.0.11:5025 Route 1 0 3 ... My client program is sending TCP requests to 10.1.0.254:5025, usually getting a good response but sometimes a bad response. With this few servers, I could send my request to each server in turn until I discover the culprit, but I wonder if that technique will scale as we add servers. What means exist for me to find out where requests got routed? Kernel: Linux 2.6.32 OS: Debian testing (whatever that's called these days). ipvsadm is version 1.25, compiled with ipvs v1.2.1

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• Squid with mikrotik router

  - by niren

  I tried to connect squid3 in my network to use high anonymity proxy. This is how my network is right now WAN LINK | ------------- ----------------------------- | Mikrotik Box | | Ubuntu Server with squid3 | ------------- ----------------------------- | / | / ---------------------- | Switch ( Cheap one ) | ---------------------- | | | Client1 Client2 Client3 etc. after this setup I changed squid.conf in Ubuntu server as http_port 8080 acl localhost src xxx.xxx.xxx.xxx(Ubuntu server IP) acl to_localhost dst xxx.xxx.xxx.xxx(Mikrotik router gateway) I assume that redirected http from Mikrotik router will be redirect again to Mikrotik router. uncomment access log /var/log/squid3/access.log add visible_hostname myname save squid.conf and restart squid3 server. Then I have added nat rule in Mikrotik router ip/firewall/nat 1. add chain=dstnat src_address=xxx.xxx.xxx.xxx(ununtu server IP) dst-port=80 protocol=tcp action=accept 2. add chain=dstnat src_address=xxx.xxx.xxx.xxx/28(LAN address) dst-port=80 protocol=tcp action=dst-nat to-address=xxx.xxx.xxx.xxx(ununtu server IP) to-port=8080 now I can not able to access internet from client1 system, If I remove these two nat rule then I can access internet. what is wrong I have made?

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• How to route to a secondary interface on the same physical ethernet?

  - by sjose3612611

  INTERNET<->(wan)BRIDGED_DEVICE(lan)<->ETH_ROUTER<->LAN Problem: Need to access web server on BRIDGED_DEVICE's LAN from INTERNET via ROUTER (BRIDGED_DEVICE's web server cannot be accessed form INTERNET since it has no Public management IP). Cannot configure bridged device. It has a static IP on its LAN to which its web server binds. Attempt: Create a secondary/alias WAN Interface on ETH_ROUTER (e.g Primary: eth0.1 (for internet access) and Secondary: eth0.2 (for accessing web server on BRIDGED_DEVICE), (No VLANs). eth0.1 has a public IP; eth0.2 has a static private IP in the BRIDGED_DEVICE's subnet (e.g 10.0.X.Y). Iptables on ETH_ROUTER: Added a port forward (DNAT) from eth0.1 to eth0.2: iptables -t nat -I PREROUTING -i eth0.1 -p tcp --dport 80 -j DNAT --to-destination 10.0.X.Y iptables -t nat -I POSTROUTING -o eth0.2 -s 10.0.X.0/24 -j MASQUERADE Stateful firewall w/ overall drop policy on FORWARD chain, hence: iptables -I FORWARD -i eth0.1 -d 10.0.X.Y -p tcp --dport 80 -j ACCEPT Can ping from ETH_ROUTER to BRIDGED_DEVICE but unable to reach the web server from Internet. I see packet cont increasing for the DNAT rule but not sure where it disappears in the ETH_ROUTER after that. ETH_ROUTER is the only device that can be configured to achieve this. If familiar with this scenario, please suggest what I may be missing or doing wrong here or suggest techniques to debug?

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• Multiple IP's using one NIC connectivity problem - Windows

  - by Vincent

  I have a frame relay network that is directly connected to a GPRS network. I also have a ADSL high speed network and recently I have been trying to achieve the following network configuration using windows 7 (Also tried XP) with no success to date. On one server I have two NIC's NIC1 I would like the following two static IP address's 10.0.1.110 and 10.0.1.200 the cisco router has a default gateway of 10.0.1.1 the ADSL is DHCP. NIC1 and the cisco router do not have access to the internet. NIC2 is setup for DHCP with a primary DNS and secondary DNS configured to enable internet connectivity. With NIC1 all incoming TCP connections are from IP address's starting with 10.192.x.x I cannot establish a TCP connection to both 10.0.1.110 and 10.0.1.200. Its either one or the other. I have a static route implemented in windows of: route -p 10.192.0.0 mask 255.255.0.0 10.0.1.1 metric 1 I have tried leaving out the gateway in the NIC1 and many other combinations with no success. Can anyone please help? What am I doing wrong?

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• Change OpenVZ route to pass through ip failover

  - by Kevin Campion

  I have one dedicaced server with its own IP and another IP (failover) who refer to the first. I will wish to change the gateway of a Proxmox virtual machine (openvz) who runs on this dedicaced server to go through the failover IP rather than the ip of host main server. Once connected to a virtual machine, when I do a traceroute VE# traceroute www.google.fr traceroute to www.google.fr (209.85.229.104), 30 hops max, 60 byte packets 1 MY_SERVER_NAME.ovh.net (xxx.xxx.xxx.xxx FIRST_IP_MAIN_SERVER) 0.021 ms 0.010 ms 0.009 ms The first line tells me the ip of host main server. I would like that the traceroute display the second IP failover. VE# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.0.2.1 * 255.255.255.255 UH 0 0 0 venet0 default 192.0.2.1 0.0.0.0 UG 0 0 0 venet0 With iptables HOST# iptables -t nat -L Chain POSTROUTING (policy ACCEPT) target prot opt source destination MASQUERADE all -- anywhere anywhere MASQUERADE all -- anywhere anywhere SNAT tcp -- anywhere 10.10.101.2 tcp dpt:www state NEW,RELATED,ESTABLISHED,UNTRACKED to:SECOND_IP_FAILOVER SNAT all -- 10.10.101.2 anywhere to:SECOND_IP_FAILOVER 10.10.101.2 is the virtual machine IP (interface venet0) Any ideas ?

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• ISA 2000 and COD MW2 Steam

  - by twlichty

  OK, so maybe not the "proper use" of network resources, but we enjoy the odd COD game during lunch hours. When we played COD4, we had a dedicated server setup at the back of the server room. With MW2, we need to be able to connect to steam to be able to play multi-player. I've found this support article here: https://support.steampowered.com/kb%5Farticle.php?ref=8571-GLVN-8711 Which outlines all the ports I need to open. I went through and created the following rules in ISA 2000 (I'm stuck with 2000 for now). Protocol Definition: Steam Primary connection: Port 27000, UDP, Send Receive Secondary Connection: Port range 27001-27030 Send Receive Protocol Definition: Steam TCP In Primary connection: 27014, TCP, Inbound Secondary Connection: Port range: 27015-27050, Inbound Protocol Definition: Steam 4380 Primary connection: 4380, UDP, Send Receive When I start steam on my local workstation (I did add an exception to the Vista Firewall to allow steam), the steam client sits on "Updating Steam" for 5 minutes then errors out with: You must connect to the internet first. Any ideas? I assume I missed something. Thanks for your help.

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• Is iptable capable of this or should I go with mod_proxy?

  - by Jesper

  I'm trying to configure my network to receive an incoming connection on one device and then redirect it to another device on a specific port. Right now I'm on about port 80 and a device running apache. The problem I'm facing is that when the forwarding is done it also sets the source ip to the first device instead of the source ip the user that connects to the service has. Let me illustrate it: [Internet User] = 7.7.7.7 connects to [Device 1] = 1.1.1.1:80 [Device 1] forwards it to [Device 2] = 1.1.1.2:80 [Device 2] outputs response that [Internet User] sees So on [Device 2] I will naturally see [Device 1]s IP in the logs, but I wanna see if there is a way to connect the internet user through [Device 1] to [Device 2] while seeing the real source IP in the logs on [Device 2]. Is that possible? My rule-set looks like this at the moment: (on Device 1) iptables -P FORWARD ACCEPT iptables -t nat -I PREROUTING -j DNAT -p tcp --dport 80 --to-destination 1.1.1.2:80 iptables -t nat -I POSTROUTING -j SNAT -p tcp -d 1.1.1.2 --to-source 1.1.1.1 On [Device 2] it accepts all incoming on port 80 from [Device 1] as well as accepts all related and established connections. So, would there be any way to get the real source onto [Device 2]? Let me know if you need more information!

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• Translating IPTables rule to UFW

  - by Dario Fumagalli

  we are using an Ubuntu 12.04 x64 LTS VPS. Firewall being used is UFW. I have setup a Varnish + LEMP setup. along with other things, including an Openswan IPSEC VPN from our office to the VPS data center. A second in house Ubuntu box is to act as MySQL slave and fetch data from the VPS through the VPN. Master's ppp0 is seen as 10.1.2.1 from the slave, they ping etc. I have done the various required tasks but I can't get the client (slave) MySQL (nor telnet 10.1.2.1 3306) to access the master through the VPN unless I issue this fairly obvious IPTables command: iptables -A INPUT -s 10.1.2.0/24 -p tcp --dport 3306 -j ACCEPT I willingly forced the accepted input to come from the last octet. With this rule everything works just fine! However I want to translate this command to UFW syntax so to keep everything in one place. Now I admit being inexperienced with UFW, I prepared rules like: ufw allow proto tcp from 10.1.2.0/24 port mysql and 2-3 variations involving specifying 3306 instead of mysql, specifying a target IP (MySQL's my.cnf at the moment is configured as 0.0.0.0) and similar but I just don't seem to be able to replicate the simple iptables rule in a functional way. Anyone could kindly give me a suggestion that is not to dump UFW? Thanks in advance.

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• how to debug when xinetd says : got signal 17 (child exited)

  - by Faizan Shaik

  I am trying to start services vsftpd and sshd using xinetd. my config files are as follows. /etc/xinetd.conf defaults { instances = 60 log_type = FILE /var/log/xinetdlog log_on_success = HOST PID log_on_failure = HOST cps = 25 30 only_from = localhost } includedir /etc/xinetd.d /etc/xinetd.d/ftp service ftp { disable = no server = /usr/sbin/vsftpd server_args = -l user = root socket_type = stream protocol = tcp wait = no instances = 4 flags = REUSE nice = 10 log_on_success += DURATION HOST USERID only_from = 127.0.0.1 10.0.0.0/24 } /etc/xinetd.d/ssh service ssh { disable = no log_on_failure += USERID server = /usr/sbin/sshd user = root socket_type = stream protocol = tcp wait = no instances = 20 flags = REUSE only_from = 127.0.0.1 10.0.0.0/24 } Even though i've included only_from attribute, vsftp server as well as ssh server are refusing connection from localhost. while vsftp and ssh servers are working fine individually when i check with "service vsftpd start" and "service ssh start". when i did debug using "xinetd -d" throug terminal i got the output as 13/10/20@00:06:08: DEBUG: 3592 {cnf_start_services} Started service: ftp 13/10/20@00:06:08: DEBUG: 3592 {cnf_start_services} Started service: ssh 13/10/20@00:06:08: DEBUG: 3592 {cnf_start_services} mask_max = 8, services_started = 2 13/10/20@00:06:08: NOTICE: 3592 {main} xinetd Version 2.3.14 started with libwrap loadavg options compiled in. 13/10/20@00:06:08: NOTICE: 3592 {main} Started working: 2 available services 13/10/20@00:06:08: DEBUG: 3592 {main_loop} active_services = 2 13/10/20@00:06:16: DEBUG: 3592 {main_loop} select returned 1 13/10/20@00:06:16: DEBUG: 3592 {server_start} Starting service ftp 13/10/20@00:06:16: DEBUG: 3592 {main_loop} active_services = 2 13/10/20@00:06:16: DEBUG: 3607 {exec_server} duping 9 13/10/20@00:06:16: DEBUG: 3592 {main_loop} active_services = 2 13/10/20@00:06:16: DEBUG: 3592 {main_loop} select returned 1 13/10/20@00:06:16: DEBUG: 3592 {check_pipe} Got signal 17 (Child exited) 13/10/20@00:06:16: DEBUG: 3592 {child_exit} waitpid returned = 3607 13/10/20@00:06:16: DEBUG: 3592 {server_end} ftp server 3607 exited 13/10/20@00:06:16: DEBUG: 3592 {svc_postmortem} Checking log size of ftp service 13/10/20@00:06:16: INFO: 3592 {conn_free} freeing connection 13/10/20@00:06:16: DEBUG: 3592 {child_exit} waitpid returned = -1 both services are getting started but neither of them is working. after banging for 3-4 hours i still don't have any clue about this error. Any help would be appreciated. thanks!

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• Server 2012, Jumbo Frames - should I expect problems?

  - by TomTom

  Ok, this sound might stupid - but is there any negative on just enabling jumbo frames in practice? From what I understand: Any switch or ethernet adapter that sees a jumbo frame it can not handle will just drop it. TCP is not a problem as max frame size is negotiated in the setinuo phase. UCP is a theoretical problem as a server may just send a LARGE UDP packet that gets dropped on the way. Practically though, as UDP is packet based, I do not really think any software WOULD send a UDP packet larger than 1500 bytes net without app level configuration changes - at least this is how I do my programming, as it is quite hard to get a decent MTU size for that without testing yourself, so you fall back in programming to max 1500 packets. The network in question is a standard small business network - we upgraded now from a non managed 24 port switch to a 52 port switch with 4 10g ports (netgear - quite cheap) and will mov a file server to 10g for also ISCSI serving. All my equipment on the Ethernet level can handle minimum 9000 bytes and due to local firewalls I really want to get packets larger (less firewall processing), but the network is also NAT'ed to the internet. On top, different machines move around (download) large files (multi gigabyte area) quite often for processing. The question is - can I expect problems when I just enable jumbo frames? Again, this is not totally ignorance - I just don't see programs sending more than 1500 byte UDP packets (if that is a practical problem please tell me) and for TCP the MTU is negotiated anyway. if there is a problem I can move to a dedicated VLAN, but this has it's own shares of problems as basically most workstations must then be on both VLAN's.

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• iptables secure squid proxy

  - by Lytithwyn

  I have a setup where my incoming internet connection feeds into a squid proxy/caching server, and from there into my local wireless router. On the wan side of the proxy server, I have eth0 with address 208.78.∗∗∗.∗∗∗ On the lan side of the proxy server, I have eth1 with address 192.168.2.1 Traffic from my lan gets forwarded through the proxy transparently to the internet via the following rules. Note that traffic from the squid server itself is also routed through the proxy/cache, and this is on purpose: # iptables forwarding iptables -A FORWARD -i eth1 -o eth0 -s 192.168.2.0/24 -m state --state NEW -j ACCEPT iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A POSTROUTING -t nat -j MASQUERADE # iptables for squid transparent proxy iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j DNAT --to 192.168.2.1:3128 iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128 How can I set up iptables to block any connections made to my server from the outside, while not blocking anything initiated from the inside? I have tried doing: iptables -A INPUT -i eth0 -s 192.168.2.0/24 -j ACCEPT iptables -A INPUT -i eth0 -j REJECT But this blocks everything. I have also tried reversing the order of those commands in case I got that part wrong, but that didn't help. I guess I don't fully understand everything about iptables. Any ideas?

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• iptables rules to allow HTTP traffic to one domain only

  - by Emily

  Hi everyone, I need to configure my machine as to allow HTTP traffic to/from serverfault.com only. All other websites, services ports are not accessible. I came up with these iptables rules: #drop everything iptables -P INPUT DROP iptables -P OUTPUT DROP #Now, allow connection to website serverfault.com on port 80 iptables -A OUTPUT -p tcp -d serverfault.com --dport 80 -j ACCEPT iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT #allow loopback iptables -I INPUT 1 -i lo -j ACCEPT It doesn't work quite well: After I drop everything, and move on to rule 3: iptables -A OUTPUT -p tcp -d serverfault.com --dport 80 -j ACCEPT I get this error: iptables v1.4.4: host/network `serverfault.com' not found Try `iptables -h' or 'iptables --help' for more information. Do you think it is related to DNS? Should I allow it as well? Or should I just put IP addresses in the rules? Do you think what I'm trying to do could be achieved with simpler rules? How? I would appreciate any help or hints on this. Thanks a lot!

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• ports only available from the outside network

  - by ChrisJ

  This is a counter-intuitive problem for me. I have a new Win 2003 server on a static IP address w.x.y.z. Tomcat 7, PostgreSQL 9.1, and Subversion are installed. All of it appears to be working fine from the server itself. We can also access the Tomcat manager, web applications, and run "svn ls svn://w.x.y.z/" from outside our network. However, when I try from another machine in the office, phpPgAdmin and svn cannot establish connections with the server. http://w.x.y.z:5432/phppgadmin cannot connect. The svn command from above returns: svn: E730061: Unable to connect to a repository at URL 'svn://w.x.y.z/' svn: E730061: Can't connect to host 'w.x.y.z': No connection could be made because the target machine actively refused it. Tomcat manager and the other web apps we have deployed work fine. Netstat -a from the server shows this: Proto Local Address Foreign Address State TCP SERVERNAME:3690 SERVERNAME:0 LISTENING TCP SERVERNAME:5432 SERVERNAME:0 LISTENING Windows Firewall was off, but just in case I also tried to enable it and open ports 3690 (svn) and 5432 (postgres). No change. I don't have access to the router/switch because it just doesn't work that way in Port-au-Prince and our sysadmin is on R&R. Is there anything that might be causing the problem from the server side?

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• Postfix "loops back to myself" error on relay to another IP address on same machine

  - by Nic Wolff

  I'm trying to relay all mail for one domain "ourdomain.tld" from Postfix running on port 2525 of one interface to another SMTP server running on port 25 of another interface on the same machine. However, when a message is received for that domain, we're getting a "mail for loops back to myself" error. Below are netstat and postconf, the contents of our /etc/postfix/transport file, and the error that Postfix is logging. (The high bytes of each IP address are XXXed out.) Am I missing something obvious? Thanks - # netstat -ln -A inet Proto Recv-Q Send-Q Local Address Foreign Address State ... tcp 0 0 XXX.XXX.138.209:25 0.0.0.0:* LISTEN tcp 0 0 XXX.XXX.138.210:2525 0.0.0.0:* LISTEN # postconf -d | grep mail_version mail_version = 2.8.4 # postconf -n alias_maps = hash:/etc/aliases allow_mail_to_commands = alias,forward bounce_queue_lifetime = 0 command_directory = /usr/sbin config_directory = /etc/postfix daemon_directory = /usr/libexec/postfix data_directory = /var/lib/postfix debug_peer_level = 2 default_privs = nobody default_process_limit = 200 html_directory = no inet_interfaces = XXX.XXX.138.210 local_recipient_maps = local_transport = error:local mail delivery is disabled mail_owner = postfix mailbox_size_limit = 0 mailq_path = /usr/bin/mailq manpage_directory = /usr/local/man message_size_limit = 10240000 mydestination = mydomain = ourdomain.tld myhostname = ourdomain.tld mynetworks = XXX.XXX.119.0/24, XXX.XXX.138.0/24, XXX.XXX.136.128/25 myorigin = ourdomain.tld newaliases_path = /usr/bin/newaliases queue_directory = /var/spool/postfix readme_directory = /etc/postfix recipient_delimiter = + relay_domains = ourdomain.tld relay_recipient_maps = sample_directory = /etc/postfix sendmail_path = /usr/sbin/sendmail setgid_group = postdrop smtpd_authorized_verp_clients = $mynetworks smtpd_recipient_limit = 10000 transport_maps = hash:/etc/postfix/transport unknown_local_recipient_reject_code = 450 # cat /etc/postfix/transport ourdomain.tld relay:[XXX.XXX.138.209]:25 # tail -f /var/log/maillog ... Aug 2 23:58:36 va4 postfix/smtp[9846]: 9858A758404: to=<nicwolff@... >, relay=XXX.XXX.138.209[XXX.XXX.138.209]:25, delay=1.1, delays=0.08/0.01/1/0, dsn=5.4.6, status=bounced (mail for [XXX.XXX.138.209]:25 loops back to myself)

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• Not getting gigbit from a gigabit link?

  - by marcusw

  I just upgraded my LAN to gigabit. This is what netperf has to say about things. Before: marcus@lt:~$ netperf -H 192.168.1.1 TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.1.1 (192.168.1.1) port 0 AF_INET : demo Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.02 94.13 After: marcus@lt:~$ netperf -H 192.168.1.1 TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.1.1 (192.168.1.1) port 0 AF_INET : demo Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.01 339.15 Only 340 Mbps? What's up with that? Background info: I'm connecting through a gigabit switch to a sheevaplug. I have Cat5e wiring in the walls and the run is maybe 30 feet. If you're not familiar with netperf, it has a tendency to give very stable results and never lie.

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• CentOS iscsi initiator has session but there is no block device

  - by jcalfee314

  I have installed the scsi-target-utils package on CentOS and I used it to perform a discovery. The discovery did give me an active session. I restarted the iscsi service but I do not see any new devices (fdisk -l). I see in /var/log/messages that my connection is operational now. I'm not sure how to debug this further. Can someone direct me into fixing this? discovery: iscsiadm -m discovery -t sendtargets -p 192.168.0.155 returns: 192.168.0.155:3260,-1 iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3 Just to verify it actually worked: iscsiadm -m session returns tcp: [1] 192.168.0.155:3260,1 iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3 restarting as the directions say to do: service iscsi restart output written to /var/log/message Stopping iscsi: Sep 20 12:14:22 localhost kernel: connection1:0: detected conn error (1020) [ OK ] Starting iscsi: Sep 20 12:14:22 localhost kernel: scsi1 : iSCSI Initiator over TCP/IP Sep 20 12:14:22 localhost iscsid: Connection1:0 to [target: iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3, portal: 192.168.0.155,3260] through [iface: default] is shutdown. Sep 20 12:14:22 localhost iscsid: Could not set session2 priority. READ/WRITE throughout and latency could be affected. [ OK ] [root@db iscsi]# Sep 20 12:14:23 localhost iscsid: Connection2:0 to [target: iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3, portal: 192.168.0.155,3260] through [iface: default] is operational now Ran a login command: iscsiadm -m node -T iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3 -p 192.168.0.155 -l No errors, no logging occurred. Next I compared the output from "fdisk -l|egrep dev" both with the iscsi session and without. There is no difference. I suppose I could just look in /etc/mtab. Any ideas on how I can get an iscsi device?

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• Preventing DDOS/SYN attacks (as far as possible)

  - by Godius

  Recently my CENTOS machine has been under many attacks. I run MRTG and the TCP connections graph shoots up like crazy when an attack is going on. It results in the machine becoming inaccessible. My MRTG graph: mrtg graph This is my current /etc/sysctl.conf config # Kernel sysctl configuration file for Red Hat Linux # # For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and # sysctl.conf(5) for more details. # Controls IP packet forwarding net.ipv4.ip_forward = 0 # Controls source route verification net.ipv4.conf.default.rp_filter = 1 # Do not accept source routing net.ipv4.conf.default.accept_source_route = 0 # Controls the System Request debugging functionality of the kernel kernel.sysrq = 1 # Controls whether core dumps will append the PID to the core filename # Useful for debugging multi-threaded applications kernel.core_uses_pid = 1 # Controls the use of TCP syncookies net.ipv4.tcp_syncookies = 1 # Controls the maximum size of a message, in bytes kernel.msgmnb = 65536 # Controls the default maxmimum size of a mesage queue kernel.msgmax = 65536 # Controls the maximum shared segment size, in bytes kernel.shmmax = 68719476736 # Controls the maximum number of shared memory segments, in pages kernel.shmall = 4294967296 net.ipv4.conf.all.rp_filter = 1 net.ipv4.tcp_syncookies = 1 net.ipv4.icmp_echo_ignore_broadcasts = 1 net.ipv4.conf.all.accept_redirects = 0 net.ipv6.conf.all.accept_redirects = 0 net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.all.rp_filter = 1 net.ipv4.tcp_max_syn_backlog = 1280 Futher more in my Iptables file (/etc/sysconfig/iptables ) I only have this setup # Generated by iptables-save v1.3.5 on Mon Feb 14 07:07:31 2011 *filter :INPUT ACCEPT [1139630:287215872] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [1222418:555508541] Together with the settings above, there are about 800 IP's blocked via the iptables file by lines like: -A INPUT -s 82.77.119.47 -j DROP These have all been added by my hoster, when Ive emailed them in the past about attacks. Im no expert, but im not sure if this is ideal. My question is, what are some good things to add to the iptables file and possibly other files which would make it harder for the attackers to attack my machine without closing out any non-attacking users. Thanks in advance!

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• Correctly setting up UFW on Ubuntu Server 10 LTS which has Nginx, FastCGI and MySQL?

  - by littlejim84

  Hello. I'm wanting to get my firewall on my new webserver to be as secure as it needs to be. After I did research for iptables, I came across UFW (Uncomplicated FireWall). This looks like a better way for me to setup a firewall on Ubuntu Server 10 LTS and seeing that it's part of the install, it seems to make sense. My server will have Nginx, FastCGI and MySQL on it. I also want to be allow SSH access (obviously). So I'm curious to know exactly how I should set up UFW and is there anything else I need to take into consideration? After doing research, I found an article that explains it this way: # turn on ufw ufw enable # log all activity (you'll be glad you have this later) ufw logging on # allow port 80 for tcp (web stuff) ufw allow 80/tcp # allow our ssh port ufw allow 5555 # deny everything else ufw default deny # open the ssh config file and edit the port number from 22 to 5555, ctrl-x to exit nano /etc/ssh/sshd_config # restart ssh (don't forget to ssh with port 5555, not 22 from now on) /etc/init.d/ssh reload This all seems to make sense to me. But is it all correct? I want to back this up with any other opinions or advice to ensure I do this right on my server. Many thanks!

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• Destination NAT Onto the Same Network from internal clients

  - by mivi

  I have a DSL router which acts as NAT (SNAT & DNAT). I have setup a server on internal network (10.0.0.2 at port 43201). DSL router was configured to "port forward" (or DNAT) all incoming connections to 10.0.0.2:43201. I created a virtual server for port forwarding on DSL router. I also added following iptables rules for port forwarding. iptables -t nat -A PREROUTING -p tcp -i ppp_0_1_32_1 --dport 43201 -j DNAT --to-destination 10.0.0.2:43201 iptables -I FORWARD 1 -p tcp -m state --state NEW,ESTABLISHED,RELATED -d 10.0.0.2 --dport 43201 -j ACCEPT # ppp_0_1_32_1 is routers external interface. # routers internal IP address is 10.0.0.1 and server is setup at 10.0.0.2:43201 Problem is that connections coming from external IP addresses are able to access internal server using External IP address, but internal clients (under NAT) are not able to access server using external IP address. Example: http://<external_address>:43201 is working from external clients But, internal clients are not able to access using http://<external_address>:43201 This seems to be similar to the problem described in http://www.netfilter.org/documentation/HOWTO/NAT-HOWTO-10.html (NAT HOW-TO Destination NAT Onto the Same Network). Firstly, I am not able to understand why is this a problem for internal clients? Secondly, what iptables rule will enable internal clients to access server using external IP address? Please suggest.

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• Microsoft Licensing Scenario/Questions [closed]

  - by user17455

  Possible Duplicate: Can you help me with my software licensing question? I am a member of a team developing a third party application (APP) that listens for and services connections from remote devices via TCP. Also, some of these remote devices allow 1 or more users to interact with the remote device. On some of the remote devices, it is impossible for a user to interact with the device. The user/remote device makes no use of any Windows Server service - not DHCP, not IIS, not File Server, not Print Serer, not AD. The remote device's only connection to the Windows Server machine is through the APP's TCP ports. Our company has no interaction with Microsoft. We do not have a Microsoft sales team. Past inquiries have determined that it is cheaper for us to buy Microsoft software (and CALs) retail than to enter into any kind of "arrangement" with Microsoft. I have many questions about SQL Server CALs and Windows Server 2008 CALs. How can I obtain authoritative/legally binding answers? I am not looking for FREE legal advice. I AM looking for FREE advice about who/what/where I can responsibly spend my money to get meaningful information. I fear that passing this on to the local company law firm will just mean that I will be paying them to educate themselves on Microsoft licensing. And if that's like writing code to a new Microsoft API - they are not going to get it right the first time. Going to Microsoft for answers sounds like swimming up to a hungry shark and asking "One leg or two?" I am hoping someone has been down this road before and knows a law firm/lawyer that is experienced in these matters. Any help/suggestion welcome. Thanks.

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• xauth, ssh and missing home directory

  - by flolo

  We have several servers, and normaly everything works fine, except now... we get a new aircondition installed. This takes 36 hours and for this time almost all servers got shutdown, only 2 remaining servers run for the most important tasks (i.e. accepting incoming email, delivering some important websites, login-server). Everybody was informed that when they need appropiate data from the homedirs they should fetch it before take down. Long story short: Someone realized that he have run a certain program on one of the servers. No Problem, he can remote login into our login server and run the programm there without home directory (binaries are local and necessary information can be copied to the /tmp). That works like a charm until... ... the user needs to run a GUI programm. I find no easy way to make it running, usually ssh -Y honk@loginserver is enough but now the homedirectory is missing and ssh is not able to copy the cookies into ~/.Xauthority (as the file server with the home directories is down). Paranoid as all systemadmins all X-Server just listen locally not on tcp ports, so no remote X connection possible SSH config is waterproof - i.e. no way to set environment variables. My Problem is, that the generated proxy MIT cookie from ssh get lost as the .Xauthority doesnt exist. If I could retrieve it somehow I could reenter it a .Xauthority in /tmp. The only other option (besides changing the config) which came to my mind is, makeing a tunnel (netcat, or better ssh) from the remote host to the loginserver and copy the cookie manually (not sure if it the tcp-unix domain socket stuff works as expected). Any good suggestions (for the future - now our servers are already up)?

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• OpenVPN Keeps Crashing

  - by Frank Thornton

  Oct 20 21:00:44 sb1 openvpn[2082]: <MY_IP>:28523 [vpntest] Peer Connection Initiated with [AF_INET]<MY_IP>:28523 Oct 20 21:00:44 sb1 openvpn[2082]: vpntest/<MY_IP>:28523 MULTI_sva: pool returned IPv4=10.8.0.6, IPv6=(Not enabled) Oct 20 21:00:44 sb1 openvpn[2082]: <MY_IP>:28522 WARNING: 'link-mtu' is used inconsistently, local='link-mtu 1576', remote='link-mtu 1376' Oct 20 21:00:44 sb1 openvpn[2082]: <MY_IP>:28522 WARNING: 'tun-mtu' is used inconsistently, local='tun-mtu 1532', remote='tun-mtu 1332' Oct 20 21:00:45 sb1 openvpn[2082]: <MY_IP>:28522 [vpntest2] Peer Connection Initiated with [AF_INET]<MY_IP>:28522 Oct 20 21:00:45 sb1 openvpn[2082]: vpntest2/<MY_IP>:28522 MULTI_sva: pool returned IPv4=10.8.0.10, IPv6=(Not enabled) Oct 20 21:00:46 sb1 openvpn[2082]: vpntest/<MY_IP>:28523 send_push_reply(): safe_cap=940 Client File: client dev tun proto tcp remote <IP> 443 resolv-retry infinite nobind tun-mtu 1500 tun-mtu-extra 32 mssfix 1410 persist-key persist-tun auth-user-pass comp-lzo SERVER: port 443 #- port proto tcp #- protocol dev tun tun-mtu 1500 tun-mtu-extra 32 reneg-sec 0 #mtu-disc yes mssfix 1410 ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt cert /etc/openvpn/easy-rsa/2.0/keys/server.crt key /etc/openvpn/easy-rsa/2.0/keys/server.key dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem plugin /etc/openvpn/openvpn-auth-pam.so /etc/pam.d/login #plugin /usr/share/openvpn/plugin/lib/openvpn-auth-pam.so /etc/pam.d/login #- Comment this line if you are using FreeRADIUS #plugin /etc/openvpn/radiusplugin.so /etc/openvpn/radiusplugin.cnf #- Uncomment this line if you are using FreeRADIUS client-to-client client-cert-not-required username-as-common-name server 10.8.0.0 255.255.255.0 push "redirect-gateway def1" push "dhcp-option DNS 8.8.8.8" push "dhcp-option DNS 8.8.4.4" keepalive 3 30 comp-lzo persist-key persist-tun What is causing the VPN to keep dropping the connection and then reconnecting?

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• Host name change breaking http? Fedora

  - by Dave

  OK so I have been messing around on my development server. It has been a while since I have had my head in linux and I suspect I have broken something. I have SSH running and that is working fine. I also have HTTP and I had FTP running also. Earlier today I decided I wanted to rename the machine so I updated the /etc/hosts file and /etc/sysconfig/network. I also changed the server name in the httpd.conf. I rebooted the machine and reconnected to SSH fine. Later I was messing around with the FTP service (trying to tighten up the user security) and when i tried to connect remotely to FTP no joy, it said cannot connect. I thought that was weird but had planned to remove ftp as we will be using github so removed ftp and moved on. Then I tried to connect to the website but major fail. even connecting to the IP address is failing. I used lynx to connect to the localhost and there was my site so something going on at server level. I thought maybe something up with iptables but I have not changed them but tried adding http but still no joy. I have a - Fedora release 17 (Beefy Miracle) NAME=Fedora VERSION="17 (Beefy Miracle)" ID=fedora VERSION_ID=17 PRETTY_NAME="Fedora 17 (Beefy Miracle)" ANSI_COLOR="0;34" CPE_NAME="cpe:/o:fedoraproject:fedora:17" Fedora release 17 (Beefy Miracle) Fedora release 17 (Beefy Miracle) Linux version 3.3.4-5.fc17.x86_64 ([email protected]) (gcc version 4.7.0 20120504 (Red Hat 4.7.0-4) (GCC) ) #1 SMP Mon May 7 17:29:34 UTC 2012 This is my iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED ACCEPT icmp -- anywhere anywhere ACCEPT all -- anywhere anywhere ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh REJECT all -- anywhere anywhere reject-with icmp-host-prohibited Chain FORWARD (policy ACCEPT) target prot opt source destination REJECT all -- anywhere anywhere reject-with icmp-host-prohibited Chain OUTPUT (policy ACCEPT) target prot opt source destination Like I say I can use SSH no issue but http although running is a no go from a remote computer. Any ideas?

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• Linux/hostapd: AP can ping clients, clients can access internet, can't access www@wlan1 with more than 5-6 packets at once

  - by mhambra

  Please edit the title, can't make it sound better. -- OP. Hi all, I have a Wifi USB dongle in a PC, that serves as an AP for laptop. wlan1: 192.168.2.1, netmask 255.255.255.0, routed: route add -net 192.168.2.0 netmask 255.255.255.0 gw 192.168.2.1 ping 192.168.2.2 (laptop): ping was ok for lot of packets. Now, I try to access 192.168.2.1:80/myindex.html (apache) from laptop, and can see that own 1kb test page. But, trying to access 192.168.2.1:80/my.jpg, I see the following: GET /my.jpg HTTP/1.1 200 OK <jpg header, about a kilobyte> <TCP packet retransmisson> <TCP packet retransmisson> <end of stream> It seems to be a hostapd's problem (networked stuff worked fine with Ad-Hoc), but it may be also forwarding/routing problem too. What to google for? Even more strange, SSH to that host works fine.

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