mjbraun's questions

I'm building a content filter for Postfix (2.9.3 package installed via apt on an Ubuntu 12.04 test VM) and I'm starting with a very basic Ruby (1.9.3) template and building up functionality. Strangely, when the script is enabled, messages sent are being forwarded on as normal, but also sent back to the sender which is not normal. Disabling the script disables this behavior. Any suggestions about what I have to change to stop that from happening? Thanks for any advice!

/etc/postfix/master.cf (only the lines changed from the default)

smtp inet  n  -  -  -  -  smtpd -o content_filter=dumper:dummy
    ...
dumper unix - n n - 10 pipe
    flags=RF user=mailuser argv=/home/mailuser/mailfilter/dumper.rb ${sender} ${recipient}`

/home/mailuser/mailfilter/dumper.rb

#!/usr/bin/env ruby
require 'open3'
dir="/home/mailuser/emails"
logfile="maillog.log"
message = $stdin.read
cmd = "/usr/sbin/sendmail -G -i  #{ARGV[0]} #{ARGV[1]}" 
stdin, stdouterr, wait_thr = Open3.popen2e(cmd)
stdin.print(message)
logfile = File.open("#{dir}/#{logfile}", 'a')
logfile.write(stdouterr)
stdin.close
stdouterr.close
exit(0)

While not intending to cross-post, after sending this question to the OpenSSH list on SecurityFocus, I noticed that the list is rather low traffic (the previous post was approximately 5 months prior). That being said, I decided to repost here as the issue will probably get more eyeballs (and will stand a better chance of being of use to others if answered):

The issue: I have a reverse SSH tunnel from an internal machine to a host in my DMZ which is set to launch at system boot and relaunch if the tunnel fails. However, when the tunnel is interrupted (for example, due to a network outage), it cannot reestablish due to the port on the DMZ host being in use. From my read of the OpenSSH mailing list archives and elsewhere, this appears to be because the port is in a TIME_WAIT state. This is fine: I can put in a sleep statement in the script that sets up the tunnel. However, this leads to two questions:

1) Any idea how to determine what the TIME_WAIT interval is defined as on a particular Linux (or other) system? While I could just sleep for 5 minutes and be fine, it would be good to shave off as much time as possible.

2) While OpenSSH doesn't appear to support the "ClearAllForwardings" option, is there similar functionality whereby an auth'd connection can automatically teardown and recreate an existing connection it had previously established?

A long sleep would probably be "good enough" but I'd prefer to handle the TIME_WAIT condition in a more efficient manner if possible.

I appreciate any guidance or suggestions!

I have a multihomed linux box with 6 network interfaces that I'm using to run some tests of router hardware. I would like to be able to set "NIC affinity" (for lack of a better term) on an arbitrary process so that even though a destination IP might correspond to a local interface, all network traffic for that process will be routed out via another interface (and looped back in by the external device). Ideally, one process's affinity setting will not affect another's.

As a sample use case, say I have eth0=192.168.0.1 and eth1=10.0.0.1. and an external router connected to eth0 and eth1 with the IPs of 192.168.0.2 and 10.0.0.2, respectively. If I open up my shell and ping 10.0.0.1, no traffic will traverse the external connection as the destination corresponds to the local machine, but if I were to somehow set the shell process's affinity to eth0, ICMP traffic would flow out via eth0, into the external router, and back again to eth1. It's the traversal of the external router that I want to guarantee, and as there will be more than one, I need to be able to bind to arbitrary NICs.

Is this possible? Given my searches thus far, I see no answers but the absence of mentions of what I'm trying to do leads me to suspect I'm missing an important consideration, as this doesn't seem like a original question (just an odd one).

FWIW, this is an Ubuntu Linux 11.10 box. Any pointers to similar work or suggestions for tools would be greatly appreciated. Thanks!

I have a webcam connected to a lightweight system (BeagleBoard) running Angstrom and I'd like to serve the webcam traffic up to one or more viewers. The problem I face is threefold: 1) I want random viewers to come and go without having to stream to dedicated destination IPs 2) I need to lighten the load (processor and network) on the BeagleBoard, so I think it would be best to have a multi-tiered stream-and-forward approach from the BeagleBoard to a middle server and then out to the viewers 3) Preferably, the end stream would be viewable in an embedded plugin.

It looks like Red5 on my middle-tier server plus VLC streaming over http from the embedded system might work, but I'm not sure if there's a smart way to go about doing this or if Red5 can do the forwarding as I envision.

Honestly, I'm rather out of my element here, and even pointers to good starting places would be appreciated. Also, latency isn't a big concern as this only needs to be "mostly-live".