Re: Problem setting up poptop on RHEL5

Charlie Brady <[email protected]>
Newsgroups gmane.network.poptop
Message-ID <[email protected]>
On Wed, 31 Aug 2011, Steve Phillips wrote:

> With the client connecting to one of the ip-aliased addresses I get the 
> following tcpdump
> 
> [root@wibble ppp]# tcpdump -i eth0:3 -n proto 47

You should collect ICMP as well

> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth0:3, link-type EN10MB (Ethernet), capture size 96 bytes
...
> In the /var/log/messages log, I get ..
> 
> Aug 31 01:26:43 wibble pppd[31310]: sent [LCP ConfReq id=0x1 <asyncmap 
> 0x0> <magic 0xd4d3a867> <pcomp> <accomp>]
> Aug 31 01:26:43 wibble pptpd[31309]: GRE: 
> read(fd=7,buffer=80515e0,len=8260) from network failed: status = -1 
> error = Protocol not available

This means that the remote end has sent back an ICMP "Protocol not 
available" packet. That's most likely because the client is behind a 
firewall/NAT router, and the firewall/router either won't accept GRE, or 
(more likely) will only accept GRE after seeing an outbound packet from 
the client to the server.

Try 'passive' in the config on the server.

--
Charlie


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