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• Steps to deploy a custom routing protocol

  - by user134589

  I'm a Ph.D Student and I'm researching a Service Centric Networking architecture with resourceallocation on a large scale. What I'm looking to do is expand an existing routing protocol like OSPF with extra fields and some new message types that I need for communication between Nodes. I want to manipulate the cost of a network link and I want paths to be calculated like in OSPF V2/v3, but using the cost that my algorithms have calculated. What I have I have the source code of OSPF from Quagga. I am assuming I can edit this code how I want, including packet structures and creating new types. Yes, I am aware it won't be easy but this is a 6 years research project and I am eager to develop something new, to move forward. What I need I would like to know how I can deploy the edited OSPF source files I have (written in C) on any type of server. I have a large testbed environment available with hundreds of virtual nodes and pretty much any OS out there. So if I want to test my extended protocol, how do I make all the nodes in a network use this to communicate? I do not understand what parts of the kernel I need to edit here. I tried searching for days now and I am unable to find how to deploy a non-existing routing protocol, without the use of an application-level framework. If somebody could push me in the right direction that'd be awesome. note: I need this to be a routingprotocol and not an application, since I want this to work on op of the network layer for performance reasons. Thanks!

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• VMWare use of Gratuitous ARP REPLY

  - by trs80

  I have an ESXi cluster that hosts several Windows Server VMs and around 30 Windows workstation VMs. Packet captures show a high number of ARP replies of the form: -sender_ip: VM IP -sender_mac: VM virtual MAC -target_ip: 0.0.0.0 -target_mac: Switch interface MAC The specific addresses aren't really a concern -- they're all legitimate and we're not having any problems with communications (most of the questions surrounding GARP and VMWare have to do with ping issues, a problem we don't have). I'm looking for an explanation of the traffic pattern in an environment that functions as expected. So the question is why would I see a high number of unsolicited ARP replies? Is this a mechanism VMWare uses for some purpose? What is it? Is there an alternative? EDIT: Quick diagram: [esxi]--[switch vlan]--[inline IDS]--[fw]--(rest of network) The IDS is complaining about these unsolicited ARPs. Several IDS vendors trigger on ARP replies without a prior request, or for ARP replies that have a target IP of 0.0.0.0. The target MAC in these replies is the VLAN interface on the switch. Capture points: -The IDS grabs the offending packets -The FW can see the same ones -A VM on the ESXi host does not see these, although there is an ARP request for a specific IP on the ESXi host that has source_ip=0.0.0.0 and source_mac=[switch vlan interface]. I can't share the captures, unfortunately. Really I'm interested in finding out if this is normal for an ESXi deployment.

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• virtualized windows 2003 domain with CentOS 5.3 and poor connectivity

  - by Chris Gow

  I have a test lab set up running a virtualized windows 2003 domain on a CentOS 5.3(xen) host and am experiencing connectivity problems with guests running on other hosts that are part of the same domain. Here's the setup: On Computer A I have CentOS 5.3 running as the host and have virtualized windows 2003 servers for a primary domain controller, a backup domain controller and an exchange server. The primary domain controller also acts as a WINS and dns server. The windows domain appears on a separate subnet from my company's corporate network. Connectivity to any of the virtualized guests on Computer A is fine (remote desktop, ping, what have you). I have another host computer (Computer B) that also has a virtualized Windows 2003 server guest that is part of the same domain. However, connectivity to that guest is flaky at best. I continuously get at least 60% packet loss when I try to ping the guest, and due to that flakiness I can not access any of the services that it runs (remote desktop, web). Now here's the interesting part. It seems to affect only machines running on a different computer than the domain controller that are in the same domain. On Computer B there is another Windows 2003 guest that is not part of the test domain and is on my corporate network. There's no connectivity issues with that guest machine. The problem does not seem to be specific to Computer B either. I created a test VM on my local computer within the test domain and it exhibits the same behaviour as the guest in Computer B. A couple of items to note: - Host OS on both Computer A and B are the same CentOS 5.3 64 bit - Guest OS is Windows 2003 64 bit and 32 bit (the guest on Computer B is 32 bit) - Guest OSes are all up to date (as of Monday) - Host OS on Computer A was upgraded from CentOS 5.2 to 5.3 Update: Sorry I did not follow up with the comments from below. Computer A and B have been moved to their own dedicated switch and the problem has gone away. I'm not sure what the underlying problem(s) were though

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• Xen virtual host can reach some sites but not others

  - by Tun H S Lee

  Okay, this is killing me. Debian Squeeze, Xen 4.0, brand new install. No iptables rules whatsoever except for the ones added by the default xen bridge script. Dom0 can reach the entire world, no problems. DomU can receive packets from some hosts, but not from others. For instance, if I ping Host A, it works fine. If I ping Host B, the DomU reports 100% packet loss. The hosts are random, but consistent (even after reboots). I can see no pattern to why some work and others don't. In fact, in some cases, different virtual hosts on the same server (an other server at a different data center) are divided; some work and others do not. I can reboot (DomU or Dom0 too) and the same hosts will work or fail as before. If I tcpdump on the Host B while pinging from the DomU, everything looks fine. It sees the echo request coming in and says it's sending one back. However, if I tcpdump peth0 on the Dom0, it never sees the echo reply. Any ideas what could be happening? I'm tearing my hair out here.

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• Windows Server 2003 IPSec Tunnel Connected, But Not Working (Possibly NAT/RRAS Related)

  - by Kevinoid

  Configuration I have setup a "raw" IPSec tunnel between a Windows Server 2003 (SBS) machine and a Netgear FVG318 according to the instructions in Microsoft KB816514. The configuration is as follows (using the same conventions as the article): NetA | SBS2003 | FVG318 | NetB 10.0.0.0/24 | 216.x.x.x | 69.y.y.y | 10.0.254.0/24 Both the Main Mode and Quick Mode Security Associations are successfully completed and appear in the IP Security Monitor. I am also able to ping the SBS2003 server on its private address from any computer on NetB. The Problem Any traffic sent from a computer on NetA to NetB, or from SBS2003 to NetB (excluding ICMP Ping responses), is sent out on the public network interface outside the IPSec tunnel (no encryption or header authentication, as if the tunnel were not there). Pings sent from a computer on NetB to a computer on NetA successfully reach computers on NetA, but the responses are silently discarded by SBS2003 (they do not go out in the clear and do not generate any encrypted traffic). Possible Solutions Incorrect Configuration I could have mistyped something, somewhere, or KB816514 could be incorrect in some way. I have tried very hard to eliminate the first option. Have re-created the configuration several times, tried tweaking and adjusting all the settings I could without success (most prevent the SA from being established). NAT/RRAS I have seen multiple posts elsewhere suggesting that this could be due to interaction between NAT and the IPSec filters. Possibly the NetA private addresses get rewritten to 216.x.x.x before being compared with the Quick Mode IPSec filters and don't get tunneled because of the mismatch. In fact, The Cable Guy article from June 2005 "TCP/IP Packet Processing Paths" suggests that this is the case, (see step 2 and 4 of the Transit Traffic path). If this is the case, is there a way to exclude NetA-NetB traffic from NAT? Any thoughts, ideas, suggestions, and/or comments are appreciated.

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• Bandwidth monitoring with iptables for non-router machine

  - by user1591276

  I came across this tutorial here that describes how to monitor bandwidth using iptables. I wanted to adapt it for a non-router machine, so I want to know how much data is going in/coming out and not passing through. Here are the rules I added: iptables -N ETH0_IN iptables -N ETH0_OUT iptables -I INPUT -i eth0 -j ETH0_IN iptables -I OUTPUT -o eth0 -j ETH0_OUT And here is a sample of the output: user@host:/tmp$ sudo iptables -x -vL -n Chain INPUT (policy ACCEPT 1549 packets, 225723 bytes) pkts bytes target prot opt in out source destination 199 54168 ETH0_IN all -- eth0 * 0.0.0.0/0 0.0.0.0/0 Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 1417 packets, 178128 bytes) pkts bytes target prot opt in out source destination 201 19597 ETH0_OUT all -- * eth0 0.0.0.0/0 0.0.0.0/0 Chain ETH0_IN (1 references) pkts bytes target prot opt in out source destination Chain ETH0_OUT (1 references) pkts bytes target prot opt in out source destination As seen above, there are no packet and byte values for ETH0_IN and ETH0_OUT, which is not the same result in the tutorial I referenced. Is there a mistake that I made somewhere? Thanks for your time.

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• Is this a good starting point for iptables in Linux?

  - by sbrattla

  Hi, I'm new to iptables, and i've been trying to put together a firewall which purpose is to protect a web server. The below rules are the ones i've put together so far, and i would like to hear if the rules makes sense - and wether i've left out anything essential? In addition to port 80, i also need to have port 3306 (mysql) and 22 (ssh) open for external connections. Any feedback is highly appreciated! #!/bin/sh # Clear all existing rules. iptables -F # ACCEPT connections for loopback network connection, 127.0.0.1. iptables -A INPUT -i lo -j ACCEPT # ALLOW established traffic iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # DROP packets that are NEW but does not have the SYN but set. iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP # DROP fragmented packets, as there is no way to tell the source and destination ports of such a packet. iptables -A INPUT -f -j DROP # DROP packets with all tcp flags set (XMAS packets). iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP # DROP packets with no tcp flags set (NULL packets). iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP # ALLOW ssh traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport ssh -m limit --limit 1/s -j ACCEPT # ALLOW http traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport http -m limit --limit 5/s -j ACCEPT # ALLOW mysql traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport mysql -m limit --limit 25/s -j ACCEPT # DROP any other traffic. iptables -A INPUT -j DROP

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• Set primary group of file or directory on Samba share from Windows

  - by Hubert Kario

  Short version: I have such situation on a Samba share: $ ls -lha total 12K drwxr-xr-x 3 hka Domain Users 4.0K Jan 11 17:07 . drwxrwxrwt 19 root root 4.0K Jan 11 17:06 .. drwxr-xr-x 2 hka Domain Users 4.0K Jan 11 17:07 dir A -rw-r--r-- 1 hka Domain Users 0 Jan 11 17:07 file A How am I able to change this to following using only Windows SMB/CIFS client (using 3rd party applications is OK) $ ls -lha total 12K drwxr-xr-x 3 hka Domain Users 4.0K Jan 11 17:07 . drwxrwxrwt 19 root root 4.0K Jan 11 17:06 .. drwxr-xr-x 2 hka ntpoweruser 4.0K Jan 11 17:07 dir A -rw-r--r-- 1 hka ntpoweruser 0 Jan 11 17:07 file A Rationale and background info I'm using POSIX ACLs on Samba shares. Together with acl group control for Samba, it allows me to delegate management of permissions to different users based on group membership. Thing is, when I create a new file on a Samba share, I'm unable to set its primary group (the one that grants permission to change its permissions). It's being set to my primary group (Domain Users) or group set using force group option in smb.conf share definition. Removing all groups in windows except the one I want to become the new primary group doesn't work. I can change it using chgrp group folder/ as regular user though shell, but it's suboptimal (not all users are *nix users). Trying to set new owner to group from Windows file permission window makes the Samba to return permission denied with following log entry: [2012/01/05 21:13:03.349734, 3] smbd/nttrans.c:1899(call_nt_transact_set_security_desc) call_nt_transact_set_security_desc: file = projects/project A/New folder, sent 0x1 [2012/01/05 21:13:03.349774, 3] smbd/posix_acls.c:1208(unpack_nt_owners) unpack_nt_owners: unable to validate owner sid for S-1-5-21-4526631811-884521863-452487935-11025 [2012/01/05 21:13:03.349804, 3] smbd/error.c:80(error_packet_set) error packet at smbd/nttrans.c(1909) cmd=160 (SMBnttrans) NT_STATUS_INVALID_OWNER The SID is correct and belongs to group I specified in GUI.

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• Redirecting or routing all traffic to OpenVPN on a Mac OS X client

  - by sdr56p

  I have configured an OpenVPN (2.2.1) server on an Ubuntu virtual machine in the Amazon elastic compute cloud. The server is up and running. I have installed OpenVPN (2.2.1) on a Mac OS X (10.8.2) client and I am using the openvpn2 binary to connect (in opposition to other clients like Tunnelblick or Viscosity). I can connect with the client and successfully ping or ssh the server through the tunnel. However, I can't redirect all internet traffic through the VPN even if I use the push "redirect-gateway def1 bypass-dhcp" option in the server.conf configurations. When I connect to the server with these configurations, I get a successful connection, but then an infinite series of error messages: "write UDPv4: No route to host (code=65)". Traffic routing seems to be compromised because I am not able to access anything anymore, not even the OpenVPN server (by pinging 10.8.0.1 for instance). This is beyond me. I am finding little help on the web and don't know what to try next. I don't think it is a problem of forwarding the traffic on the server since, first, I have also took care of that and, second, I can't even ping the VPN server locally through the tunnel (or ping anything at all for that matter). Thank you for your help. Here is the server.conf. file: port 1194 proto udp dev tun ca ca.crt cert ec2-server.crt key ec2-server.key # This file should be kept secret dh dh1024.pem server 10.8.0.0 255.255.255.0 ifconfig-pool-persist ipp.txt push "redirect-gateway def1 bypass-dhcp" client-to-client keepalive 10 120 comp-lzo persist-key persist-tun status openvpn-status.log verb 3 And the client.conf file: client dev tun proto udp remote servername.com 1194 resolv-retry infinite nobind persist-key persist-tun ca ca.crt cert Toto5.crt key Toto5.key ns-cert-type server comp-lzo verb 3 Here is the connection log with the error messages: $ sudo openvpn2 --config client.conf Wed Mar 13 22:58:22 2013 OpenVPN 2.2.1 x86_64-apple-darwin12.2.0 [SSL] [LZO2] [eurephia] built on Mar 4 2013 Wed Mar 13 22:58:22 2013 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables Wed Mar 13 22:58:22 2013 LZO compression initialized Wed Mar 13 22:58:22 2013 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ] Wed Mar 13 22:58:22 2013 Socket Buffers: R=[196724->65536] S=[9216->65536] Wed Mar 13 22:58:22 2013 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ] Wed Mar 13 22:58:22 2013 Local Options hash (VER=V4): '41690919' Wed Mar 13 22:58:22 2013 Expected Remote Options hash (VER=V4): '530fdded' Wed Mar 13 22:58:22 2013 UDPv4 link local: [undef] Wed Mar 13 22:58:22 2013 UDPv4 link remote: 54.234.43.171:1194 Wed Mar 13 22:58:22 2013 TLS: Initial packet from 54.234.43.171:1194, sid=ffbaf343 d0c1a266 Wed Mar 13 22:58:22 2013 VERIFY OK: depth=1, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain Wed Mar 13 22:58:22 2013 VERIFY OK: nsCertType=SERVER Wed Mar 13 22:58:22 2013 VERIFY OK: depth=0, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain Wed Mar 13 22:58:23 2013 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key Wed Mar 13 22:58:23 2013 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Wed Mar 13 22:58:23 2013 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key Wed Mar 13 22:58:23 2013 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Wed Mar 13 22:58:23 2013 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA Wed Mar 13 22:58:23 2013 [ec2-server] Peer Connection Initiated with 54.234.43.171:1194 Wed Mar 13 22:58:25 2013 SENT CONTROL [ec2-server]: 'PUSH_REQUEST' (status=1) Wed Mar 13 22:58:25 2013 PUSH: Received control message: 'PUSH_REPLY,route 10.8.0.0 255.255.255.0,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5' Wed Mar 13 22:58:25 2013 OPTIONS IMPORT: timers and/or timeouts modified Wed Mar 13 22:58:25 2013 OPTIONS IMPORT: --ifconfig/up options modified Wed Mar 13 22:58:25 2013 OPTIONS IMPORT: route options modified Wed Mar 13 22:58:25 2013 ROUTE default_gateway=0.0.0.0 Wed Mar 13 22:58:25 2013 TUN/TAP device /dev/tun0 opened Wed Mar 13 22:58:25 2013 /sbin/ifconfig tun0 delete ifconfig: ioctl (SIOCDIFADDR): Can't assign requested address Wed Mar 13 22:58:25 2013 NOTE: Tried to delete pre-existing tun/tap instance -- No Problem if failure Wed Mar 13 22:58:25 2013 /sbin/ifconfig tun0 10.8.0.6 10.8.0.5 mtu 1500 netmask 255.255.255.255 up Wed Mar 13 22:58:25 2013 /sbin/route add -net 10.8.0.0 10.8.0.5 255.255.255.0 add net 10.8.0.0: gateway 10.8.0.5 Wed Mar 13 22:58:25 2013 Initialization Sequence Completed ^CWed Mar 13 22:58:30 2013 event_wait : Interrupted system call (code=4) Wed Mar 13 22:58:30 2013 TCP/UDP: Closing socket Wed Mar 13 22:58:30 2013 /sbin/route delete -net 10.8.0.0 10.8.0.5 255.255.255.0 delete net 10.8.0.0: gateway 10.8.0.5 Wed Mar 13 22:58:30 2013 Closing TUN/TAP interface Wed Mar 13 22:58:30 2013 SIGINT[hard,] received, process exiting toto5:ttntec2 Dominic$ sudo openvpn2 --config client.conf --remote ec2-54-234-43-171.compute-1.amazonaws.com Wed Mar 13 22:58:57 2013 OpenVPN 2.2.1 x86_64-apple-darwin12.2.0 [SSL] [LZO2] [eurephia] built on Mar 4 2013 Wed Mar 13 22:58:57 2013 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables Wed Mar 13 22:58:57 2013 LZO compression initialized Wed Mar 13 22:58:57 2013 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ] Wed Mar 13 22:58:57 2013 Socket Buffers: R=[196724->65536] S=[9216->65536] Wed Mar 13 22:58:57 2013 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ] Wed Mar 13 22:58:57 2013 Local Options hash (VER=V4): '41690919' Wed Mar 13 22:58:57 2013 Expected Remote Options hash (VER=V4): '530fdded' Wed Mar 13 22:58:57 2013 UDPv4 link local: [undef] Wed Mar 13 22:58:57 2013 UDPv4 link remote: 54.234.43.171:1194 Wed Mar 13 22:58:57 2013 TLS: Initial packet from 54.234.43.171:1194, sid=a0d75468 ec26de14 Wed Mar 13 22:58:58 2013 VERIFY OK: depth=1, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain Wed Mar 13 22:58:58 2013 VERIFY OK: nsCertType=SERVER Wed Mar 13 22:58:58 2013 VERIFY OK: depth=0, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain Wed Mar 13 22:58:58 2013 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key Wed Mar 13 22:58:58 2013 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Wed Mar 13 22:58:58 2013 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key Wed Mar 13 22:58:58 2013 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Wed Mar 13 22:58:58 2013 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA Wed Mar 13 22:58:58 2013 [ec2-server] Peer Connection Initiated with 54.234.43.171:1194 Wed Mar 13 22:59:00 2013 SENT CONTROL [ec2-server]: 'PUSH_REQUEST' (status=1) Wed Mar 13 22:59:00 2013 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1 bypass-dhcp,route 10.8.0.0 255.255.255.0,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5' Wed Mar 13 22:59:00 2013 OPTIONS IMPORT: timers and/or timeouts modified Wed Mar 13 22:59:00 2013 OPTIONS IMPORT: --ifconfig/up options modified Wed Mar 13 22:59:00 2013 OPTIONS IMPORT: route options modified Wed Mar 13 22:59:00 2013 ROUTE default_gateway=0.0.0.0 Wed Mar 13 22:59:00 2013 TUN/TAP device /dev/tun0 opened Wed Mar 13 22:59:00 2013 /sbin/ifconfig tun0 delete ifconfig: ioctl (SIOCDIFADDR): Can't assign requested address Wed Mar 13 22:59:00 2013 NOTE: Tried to delete pre-existing tun/tap instance -- No Problem if failure Wed Mar 13 22:59:00 2013 /sbin/ifconfig tun0 10.8.0.6 10.8.0.5 mtu 1500 netmask 255.255.255.255 up Wed Mar 13 22:59:00 2013 /sbin/route add -net 54.234.43.171 0.0.0.0 255.255.255.255 add net 54.234.43.171: gateway 0.0.0.0 Wed Mar 13 22:59:00 2013 /sbin/route add -net 0.0.0.0 10.8.0.5 128.0.0.0 add net 0.0.0.0: gateway 10.8.0.5 Wed Mar 13 22:59:00 2013 /sbin/route add -net 128.0.0.0 10.8.0.5 128.0.0.0 add net 128.0.0.0: gateway 10.8.0.5 Wed Mar 13 22:59:00 2013 /sbin/route add -net 10.8.0.0 10.8.0.5 255.255.255.0 add net 10.8.0.0: gateway 10.8.0.5 Wed Mar 13 22:59:00 2013 Initialization Sequence Completed Wed Mar 13 22:59:00 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:00 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:01 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:01 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:01 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65) Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65) ... The routing table after a connection WITHOUT the push redirect-gateway (all traffic is not redirected to the VPN and everything is working fine, I can ping or ssh the OpenVPN server and access all other Internet resources through my default gateway): Destination Gateway Flags Refs Use Netif Expire default user148-1.wireless UGSc 50 0 en1 10.8/24 10.8.0.5 UGSc 2 7 tun0 10.8.0.5 10.8.0.6 UH 3 2 tun0 127 localhost UCS 0 0 lo0 localhost localhost UH 6 6692 lo0 client.openvpn.net client.openvpn.net UH 3 18 lo0 142.1.148/22 link#5 UCS 2 0 en1 user148-1.wireless 0:90:b:27:10:71 UHLWIir 50 0 en1 76 user150-173.wirele localhost UHS 0 0 lo0 142.1.151.255 ff:ff:ff:ff:ff:ff UHLWbI 0 2 en1 169.254 link#5 UCS 1 0 en1 169.254.255.255 0:90:b:27:10:71 UHLSWi 0 0 en1 71 The routing table after a connection with the push redirect-gateway option enable as in the server.conf file above (all internet traffic should be redirected to the VPN tunnel, but nothing is working, I can't access any Internet ressources at all): Destination Gateway Flags Refs Use Netif Expire 0/1 10.8.0.5 UGSc 1 0 tun0 default user148-1.wireless UGSc 7 0 en1 10.8/24 10.8.0.5 UGSc 0 0 tun0 10.8.0.5 10.8.0.6 UHr 6 0 tun0 54.234.43.171/32 0.0.0.0 UGSc 1 0 en1 127 localhost UCS 0 0 lo0 localhost localhost UH 3 6698 lo0 client.openvpn.net client.openvpn.net UH 0 27 lo0 128.0/1 10.8.0.5 UGSc 2 0 tun0 142.1.148/22 link#5 UCS 1 0 en1 user148-1.wireless 0:90:b:27:10:71 UHLWIir 1 0 en1 833 user150-173.wirele localhost UHS 0 0 lo0 169.254 link#5 UCS 1 0 en1 169.254.255.255 0:90:b:27:10:71 UHLSW 0 0 en1

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• Ping with explicit next-hop selection (aka Monitoring multiple default gateways)

  - by Michuelnik

  I have a linux (debian) router with two internet connections (A) and (B). (A) is preferred, (B) is fallback. I want to monitor the internet connection (and not only the availability of the gateways!) and change the default route appropriately. If (A) is not providing internet, switch to (B) If (A) is providing internet again, switch back to (A). Only problem I have is in case (2). My routing table points towards a working internet so I cannot easily detect whether internet is working over link (A) again. I am search for a ping or traceroute (or other diagnosis-tool) which can select the next-hop explicitly. ping -r looks promising, but can only ping a host on the lan. (It only has to write another destination address in the packet, damnit!) traceroute -g gateway looks even more promising and nearly does what I want - but sets source routing options which my next-hops deny. (Not within my administrative boundary...) I just want a $ping, that can: select a source interface (and address) select a next-hop on that interface ping any arbitrary ip address I could do evil trickery with policy-based routing but that would have production impact for all users. I would like to see a side-effect-free solution....

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• allow spoofing when using tun

  - by Johnny

  I have a working openvpn setup with a server and a number of clients. How would i go around allowing IP spoofing through the openvpn server? (to demonstrate security concepts)? A normal ping from client to server goes through all right: root@client: hping3 10.8.0.1 HPING 10.8.0.1 (tun0 10.8.0.1): NO FLAGS are set, 40 headers + 0 data bytes len=40 ip=10.8.0.1 ttl=64 DF id=0 sport=0 flags=RA seq=0 win=0 rtt=124.7 ms root@server:/etc/openvpn# tcpdump -n -i tun0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on tun0, link-type RAW (Raw IP), capture size 65535 bytes 10:17:51.734167 IP 10.8.0.6.2146 > 10.8.0.1.0: Flags [], win 512, length 0 But when spoofing a packet, it does not arrive at the openvpn server: root@client: hping3 -a 10.0.8.120 10.8.0.1 HPING 10.8.0.1 (tun0 10.8.0.1): NO FLAGS are set, 40 headers + 0 data bytes root@server:/etc/openvpn# tcpdump -n -i tun0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on tun0, link-type RAW (Raw IP), capture size 65535 bytes My current config files server.conf local X.Y.Z.P port 80 proto tcp dev tun ca ca.crt cert server.crt key server.key # This file should be kept secret dh dh1024.pem server 10.8.0.0 255.255.255.0 push "redirect-gateway def1 bypass-dhcp" keepalive 10 120 comp-lzo persist-key persist-tun persist-local-ip status openvpn-status.log verb 3 client.conf client dev tun proto tcp remote MYHOST..amazonaws.com 80 resolv-retry infinite nobind persist-key persist-tun ca ca.crt cert client.crt key client.key ns-cert-type server comp-lzo verb 3

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• Prevent Linux from processing incoming ICMP Host unreachable packets

  - by bbc

  I have a test setup with one host on a network (10.1.0.0/16) talking via TCP to another one on another network (10.2.0.0/16) and a gateway in the middle. Sometimes, the TCP connection is lost and while scanning the trace (pcap), I looks like it's because of just one ICMP Host unreachable message sent by the gateway to 10.1.0.1 at some point. 10.1.0.1 then sends a TCP RST to 10.2.0.1. In my opinion, the gateway (pfSense) is broken or not configured correctly but anyway, for testing purposes, I'd like to block this kind of ICMP on the host (10.1.0.1) before it has an influence on my TCP connection (or does it? I'm not even sure). I've tried iptables: iptables -I INPUT -i eth0 -p icmp --icmp-type host-unreachable -j DROP but while it does a good job at preventing userpace applications like ping from receiving these ICMP messages, my TCP connection still comes to an end when the alleged "killer ICMP packet" is sent by the gateway. Am I right about how it is processed? If yes, then what can I do to achieve my goal?

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• Windows Server 2008 IIS Random disconnect

  - by d123

  I am having a bit of a quirk with my IIS server. I'm running my IIS with 2 sets of IPs configured, one in the 192 range and the other in 172 range. I then have multiple apps which will talk to this server for information. Server has no AV or firewalls configured. I noticed that my apps when talking to the server on the 172 range, at random intervals, the server would just not respond. My apps would then disconnect and just try again, and every thing would be fine. This doesn't happen on the 192 range. So what I did is on a Linux box I did a watch command and to wget a file every half second on the 172 and 192 IPs. I noticed the same issue, every once in awhile wget on the 172 range would not get through, but there is no issues at all on 192. Thus I went around to Wireshark and did a dump. This is the last 3 packets, no other packets were received. 7010 100.871877 200.100.30.7 172.0.0.1 TCP 59619 http [ACK] Seq=140 Ack=85242 Win=64128 Len=0 TSV=1072818795 TSER=1660246133 7011 100.872238 200.100.30.7 172.0.0.1 TCP 59619 http [FIN, ACK] Seq=140 Ack=85242 Win=64128 Len=0 TSV=1072818796 TSER=1660246133 7013 100.873081 200.100.30.7 172.0.0.1 TCP 59619 http [ACK] Seq=141 Ack=85243 Win=64128 Len=0 TSV=1072818796 TSER=1660246133 So this is my issue, there is a random disconnect every once in awhile. The server doesn't receive the next SYN packet. HELP?

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• Windows 7 using llt for ipv6

  - by Seoman

  The question asked below is based on the specific implementations of the Os not the RFC. Looking on a way to be able to assign a fixed ip address to a host, before it boots I found that Centos 6 works fine with no modifications and Windows 7 does not work at all. As defined in enter link description here exists 3 valid ways of generate a DUID: 1 Link-layer address plus time 2 Vendor-assigned unique ID based on Enterprise Number 3 Link-layer address Looking at the centos, that works fine, I can see the following autogenerated DUID: option dhcp6.client-id 0:1:0:1:19:60:25:f1:52:54:0:6b:b9:9e; and the MAC address for this host is: ifconfig eth1 | grep HWaddr eth1 Link encap:Ethernet HWaddr 52:54:00:6B:B9:9E As you can see, the DUID containts the MAC address. I can assign a fixed ip address to this host by including an entry on my dhcp server similar to: host vm { hardware ethernet 52:54:00:6B:B9:9E; fixed-address6 2001:db8:0:1::200; if packet(0,1) = 1 { log(debug,"VM Request match!"); } } And the Centos 6 gets his ip. On the windows side, I faced a common problem explained on this other link enter link description here As summary, Win7 uses the option 2 of the DUID generation or a variation of this one. On the link explains how to move it to a llt (link layer + time) but is not working fine. If I modify the DUID to one that looks like the one generated on Centos (but with the right MAC) it works as expected. Question 1 How Can I change the DUID generation for Windows 7 to be based on MAC as Centos 6 does? Thanks

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• Many clients on a wireless AP for UDP broadcast packets

  - by distorteddisco

  I asked this question on StackOverflow and was directed over here, so I'd appreciate any advice. I'm deploying a smartphone application as part of a live music performance that depends on receiving UDP broadcast packets from a wireless access point. I'm guessing that between 20 and 50 clients will be connected at any one time. I'm aware that a maximum of 20 clients per access point is advised, but as the UDP broadcast packets are ground through the LAN, how would I be able to link multiple APs together? I'm looking for recommendations on a suitable AP for this. The actual data transmission rates are very low - only a few kB/s - as I'm just sending small messages to the smartphone apps, and there will be no WAN internet connection. I tried it with a few connected peers on an adhoc wireless connection without any problems, but ran into dropped packet issues on an old WRT54G running ddwrt, though it's in pretty rough shape. What's the best way to do this? I suppose I could limit concurrent wireless connections to 20 clients... but more would be nice. EDIT: I should also say that it's purely one-way communication; the smartphone application is only receiving broadcast packets, not sending anything.

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• [SOLVED} How do I restore my audio after uninstalling Ventrilo?

  - by Marcx

  Hi, I've a Dell studio 1555 bought on september with Windows 7 64bit Professional on it. The audio device works proprerly, while listening to audio contents (from disk or internet) When I use Ventrilo, the audio from other people sounds good and I hear their voices clearly When I use any other VOIP programs like Teamspeak 3, MSN or Skype, I hear a disturbed voice, and it's impossible to comprehend something... Anyway everything worked fine until I installed Ventrilo, but removing it didn´t solve my problem. Update: Here's a sample of how I hear others people voices.. Audio Sample After some tests, also the desktop has the same problem. (I tried TeamSpeak3) Here are some details on my laptop and desktop Laptop Dell Studio 1555 Core 2 Duo P8600 2.4Ghz 4Gb Ram Dual Channel Ati HD 4570 512Mb dedicated (up to 2048) IDT High Definition Audio Desktop Motherboard Asus P5KPL-AM Dual Core CPU E5200 2.50Ghz 2x2GB PC6400 Dual Channel Ati Radeon HD 4650 512MB VIA High Definition Audio Both computers have Windows 7 Professional 64Bit. So how do I restore my audio? SOLVED The problem was in router firmware, there was a bug that recognized VoIP traffic as a DOS attack and the router grambled every packet... I've installed the newest firmware and everything is fine :)

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• Can't Ping - Wireless network of home

  - by Naunidh

  Hello, This may seem like other ping problem, but I have tried a lot before posting it here. I have a linksys WRT54G - firmware v8.00.8. I have two laptops one windows vista (192.168.1.99) and Windows Xp (192.168.1.13) connected on WiFi . The Router's IP address is 192.168.1.4, and default gateway is the ADSL modem (192.168.1.1) connected through wire. The problem is that laptops can not ping each other, they can ping the gateway and the linksys router, and both can access internet. Following has been tried (I am pinging from XP machine to Vista): I saw that arp entires for Vista machines were not being populated, so I added static ARP entries. 192.168.1.99 00-19-7e-70-d0-4e static I checked on ethereal that an ICMP packet for MAC address of Vista machine does go out from XP machine towards the Vista machine, but never reaches the Vista machine. So its get eaten by the Router? I added Vista machine to DMZ in my linksys router, so that all the ports are open (In case it was an issue). Firewalls , antivirus etc were turned off, echo was enabled explicitly on vista, file sharing, network discovery were turned on. Network type was set to private. Unchecked everything in Router;s firewall, even though they are only meant for WAN requests. Is there anything else that I should try. Thanks.

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• Bind9 not doing anything with forwarded query responses?

  - by Rykaro

  I have a Bind DNS server that is the local production DNS server and a Windows 2008 R2 domain controller which provides DNS for a lab environment with the domain xyz.lab. I've configured the Bind DNS to forward DNS requests for the domain xyz.lab to the Windows DNS server with this config: zone "xyz.lab" { type forward; forward only; forwarders { x.x.x.x; }; }; zone "x.x.x.in-addr.arpa" { type forward; forward only; forwarders { x.x.x.x; }; }; And Bind options are (the all_internal acl includes the subnets of both the production and lab networks as well as the loopback of the bind server): allow-query { all_internal; }; allow-recursion { all_internal; }; allow-transfer { none; }; notify no; minimal-responses yes; version "unknown"; Unfortunately, when I do an nslookup or dig on the bind server for a host on the lab domain, the request times out. The logs on the Windows 2008 DNS server show it receiving the query and responding to it and a network packet trace shows the query responses arriving at the Bind DNS server. The servers reside on the same switch with a router providing connectivity between the layer 3 subnets (production and lab are on different subnets) and there is a round trip time of between 3ms and 5ms on pings between the two servers, so I don't think there is an issue with latency causing a timeout of the query. In summary a query-response arrives back at the Bind server and the nslookup/dig times-out. Why does the Bind DNS not seem to be doing anything with the query responses when it receives them?

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• Allied Telesis router: IP filtering for the LOCAL interface

  - by syneticon-dj

  Given an Allied Telesis router with an AlliedWare OS (2.9.1) I would like to disable access to all management services of the router except for a number of subnets (or alternatively have what is a "management VLAN" with other manufacturers' switch and router models). What I have tried so far: creating a new VLAN and an appropriate IP interface, setting the LOCAL IP into this subnet, creating an IP filter for the IP interface and specifying my exclusion subnets: it simply does not work as intended as I can access the LOCAL IP set from any of the other VLAN interfaces - the traffic is apparently not going through my defined filter set at all creating a new IP filter set and binding it to the LOCAL IP interface: this seems not to affect any kind of traffic at all, the counters for the filter set remain at zero packets setting the Remote Security Officer Level IP address range: this only restricts the ability for a user with the Security Officer privilege level to log in from any but the specified address ranges / subnets. Unfortunately, it does not prevent service availability (and thus DoS capacity) or the ability to log in as a less privileged user (e.g. a "manager") calling technical support: unfortunately no solution so far What I have not tried: creating a filter set for each and every IP interface defined on the router and excluding access to the router's management IP: I would like to reduce the overhead induced by IP filters as the router already is CPU-constrained at times. Setting up filters for every IP interface would mean that each and every traffic packet would have to pass the filters, thus consuming CPU cycles. If by any means possible, I would like to find a different solution.

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• Am I obliged to use ipv6 tunnel services if I want to be able to use it?

  - by Zagorax

  I was looking for configuring Slackware to use ipv6 but all instruction I found speak about using an ipv6 tunnel that encapsulate ipv6 request into ipv4 packet and send them to an external router that extracts ipv6 request and sends a reply (or, at least, this is what I understood). Is that necessary? Isn't there a way to configure a pure ipv6 system? If yes, could you please point me to a guide that clearly explain how to enable ipv6 without this trick? I would like to configure my Slackware desktop at first, and then do the same with my Centos server. EDIT: maybe I gave you too few information. Sorry. I'll write some more information thanks to the posted guide. ~$ test -f /proc/net/if_inet6 && echo "Running kernel is IPv6 ready" Running kernel is IPv6 ready So, it seems ipv6 is enabled in my kernel. Some other output from ifconfig, route and /etc/resolv.conf content (with opendns): ~$ /sbin/ifconfig wlan0 | grep inet6 inet6 addr: fe80::21f:3bff:fe60:cc5b/64 Scope:Link ~$ /sbin/route -A inet6 | grep wlan0 fe80::/64 :: U 256 0 0 wlan0 ff00::/8 :: U 256 0 0 wlan0 ~$ cat /etc/resolv.conf inet6 nameserver 2620:0:ccc::2 nameserver 208.67.222.222 nameserver 208.67.220.220 But still, with ping6 I can only ping localhost (::1). Everything else is unreachable. Normal ping works fine. That is why I was asking if I am obliged to use a tunnel.

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• What should I use to ping multiple IPs and get notified of time outs?

  - by HumanVirus

  I've been using MultiPing to ping hundreds of IPs (from access points and such) and check their performance (packet loss, latency) and uptime. The program is very easy to use, but I was wondering if someone could recommend me something that would work better and that would also work in Linux. The features I'm looking for are: Notification Types: At least desktop notifications and SMS, but it would be great if it also had e-mail, IM, or other types of notifications. (MultiPing has some of these, but they don't work too well.) Being notified about the root problem only: Since some devices are dependent on others, I'd like to be notified only about the root problem. E.g. Let's say I have A[x.x.x.222]B[x.x.x.33C[x.x.x.44]D[x.x.x.55], and B goes down, therefore C and D will also be down. Is it possible to get a notification only about B being down? Light on resources. Ideally multiplatform or at least available for both Linux and Windows. I've heard about Nagios and Shinken being used for monitoring. Would you recommend that I use something of the sort or would that be too much for my needs? If using Nagios, Shinken, or similar software is recommended, can anyone tell me what sites I should go to or what books I should get that would be good for someone who is totally new at this? I'd appreciate any suggestions.

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• How many iptables block rules is too many

  - by mhost

  We have a server with a Quad-Core AMD Opteron Processor 2378. It acts as our firewall for several servers. I've been asked to block all IPs from China. In a separate network, we have some small VPS machines (256MB and 512MB). I've been asked to block china on those VPS's as well. I've looked online and found lists which requires 4500 block rules. My question is will putting in all 4500 rules be a problem? I know iptables can handle far more rules than that, what I am concerned about is since these are blocks that I don't want to have access to any port, I need to put these rules before any allow. This means all legitimate traffic needs to be compared to all those rules before getting through. Will the traffic be noticeably slower after implementing this? Will those small VPS's be able to handle processing that many rules for every new packet (I'll put an established allow before the blocks)? My question is not How many rules can iptables support?, its about the effect that these rules will have on load and speed. Thanks.

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• Strange 3-second tcp connection latencies (Linux, HTTP)

  - by user25417

  Our webservers with static content are experiencing strange 3 second latencies occasionally. Typically, an ApacheBench run ( 10000 requests, concurrency 1 or 40, no difference, but keepalive off) looks like this: Connection Times (ms) min mean[+/-sd] median max Connect: 2 10 152.8 3 3015 Processing: 2 8 34.7 3 663 Waiting: 2 8 34.7 3 663 Total: 4 19 157.2 6 3222 Percentage of the requests served within a certain time (ms) 50% 6 66% 7 75% 7 80% 7 90% 9 95% 11 98% 223 99% 225 100% 3222 (longest request) I have tried many things: - Apache2 2.2.9 with worker or prefork MPM, no difference (with KeepAliveTimeout 10-15) - Nginx 0.6.32 - various tcp parameters (net.core.somaxconn=3000, net.ipv4.tcp_sack=0, net.ipv4.tcp_dsack=0) - putting the files/DocumentRoot on tmpfs - shorewall on or off (i.e. empty iptables or not) - AllowOverride None is on for /, so no .htaccess checks (verified with strace) - the problem persists whether the webservers are accessed directly or through a Foundry load balancer Kernel is 2.6.32 (Debian Lenny backports), but it occurred with 2.6.26 also. IPv6 is enabled, but not used. Does the issue look familiar to anyone? Help/suggestions are much appreciated. It sounds a bit like a SYN,ACK packet getting lost or ignored.

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• Configuring two subnets with two NICS. Access from a NAS to the internet

  - by archipestre

  I am having trouble configuring my NAS. I have a DSL router with WIFI (192.168.1.1) in my flatmates room. In my room I have a server with two NICS: 1) wlan0 (192.168.1.2) that connects to the DSL router via wireless 2) em1 (192.168.0.1) that connects to the NAS (192.168.0.20) with a crossover cable. I have Fedora 17 and I have enable packet forwarding. My IP configuration is as follows: WLAN0 inet 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255 EM1 inet 192.168.1.2 netmask 255.255.255.0 broadcast 192.168.1.255 My routing table looks like: Destination Gateway G enmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 wlan0 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 em1 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0 I have enable a static route in the DSL server: Status Network Destination Subnet Mask Interface Gateway Remove Edit Active 192.168.0.0 255.255.255.0 LAN 192.168.1.2 From my server I can ping the DSL router and the NAS. From the NAS I can ping both NICS of the server. However the NAS is unable to ping the DSL router or any address in the Internet. Any idea of what is wrong. Thank you in advance

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• Help - since adding an elastic load balancer to my EC2 web application I cannot connect with the MySQL database (not in AWS)

  - by undefined

  I have a web application that uses an EC2 instance to receive uploaded images, resize and store on S3 and update my MySQL database with the image record. This database is hosted outside Amazon Web Services and so obviously involves communication between the EC2 instance and the database. Images are posted to the upload server from a Flash client which receives the IP address of the upload server when it is loaded and so sends images to 1.12.23.34/resize_script.php This has worked great .. until i started to try and include a load balancer. Since the ELBs do not use an IP address but a DNS address I am now passing this to Flash. Now when I upload images I get the following response from the server - Could not connect to MySQL: Lost connection to MySQL server at 'reading initial communication packet', system error: 111 What might be causing the lost connection to MySQL server. Is there any additional steps I need to take to allow my upload servers to be load balanced? I have set the host property of my MySQL privileges for this user to % any pointers greatly appreciated thanks.

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