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I don't want to tunnel TCP over ICMP (as ptunnel does), I want to go the other way around.

I'm in the situation where I have TCP (HTTP) connectivity to a machine but an internal firewall over which I have no control is swallowing pings. The monitoring software I'm using appears to determine connectivity by attempting to send a ping before it tries to just connect to the web service on the target machine. It's failing this ping test and giving up.

I believe if I could fool my monitoring software into thinking pings were getting through, it would then connect to the web service and be on its merry way. Anyone know how I can do this?

I have SSH and root access on the destination machine.

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dunno but another way (which i also don't know) would be when A sends ping to B, if you could intercept it at A before it leaves A, and forge ping response packets with B's source IP(so as if from B), but sent to A from A. no idea how though –  barlop Nov 12 '13 at 1:02

1 Answer 1

  1. You can tunnel ICMP over TCP with any VPN software that uses TCP as a transport (the most common examples would be SSL vpns).

  2. But you don't really want to do that, cause it won't solve your problem. What kind of monitoring software are you using? Your best bet is to configure it not to require an ICMP before attempting connection, or trick it into pinging somewhere else first (maybe spood the reply when it pings).

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It's not "monitoring software" like Nagios or anything, it's a build notifier plugin for Hudson. It pinging before it tries to connect via TCP isn't an option, I'd have to fiddle the source which I haven't had the time to do. –  Robert Atkins Jan 12 '11 at 10:46
    
Well, as I mentioned, aside from tricking it by spoofing replies or using some wacky IP tables rules, there aren't a lot of choices. If you control the target machine, you could set up some VPN software on it to tunnel your ICMP, but it is probably easier to just modify your source. –  Jed Daniels Jan 13 '11 at 6:08
    
Also, thanks for introducing me to Hudson, it looks really cool and I will be looking into it further. Which Build Notifier plugin are you using? –  Jed Daniels Jan 13 '11 at 6:09

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