Lindsay, thanks for the tip, unfortunately it did not work :( :) Nes++
Lindsay Haisley wrote: > Try adding the following to your iptables rules: > > iptables -t mangle -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS > --clamp-mss-to-pmtu > > This sounds very much like the problem I had setting up a Gentoo > firewall here. The man page for iptables says: > > TCPMSS > This target allows to alter the MSS value of TCP SYN packets, to con- > trol the maximum size for that connection (usually limiting it to your > outgoing interface's MTU minus 40). Of course, it can only be used in > conjunction with -p tcp. It is only valid in the mangle table. > This target is used to overcome criminally braindead ISPs or servers > which block ICMP Fragmentation Needed packets. The symptoms of this > problem are that everything works fine from your Linux firewall/router, > but machines behind it can never exchange large packets: > 1) Web browsers connect, then hang with no data received. > 2) Small mail works fine, but large emails hang. > 3) ssh works fine, but scp hangs after initial handshaking. > Workaround: activate this option and add a rule to your firewall con- > figuration like: > iptables -t mangle -A FORWARD -p tcp --tcp-flags SYN,RST SYN \ > -j TCPMSS --clamp-mss-to-pmtu > > This fix worked for me. Issues of MTU and MTU discovery are complex. > I'm still trying to understand fully what the issues are here. > > On Tue, 2008-01-08 at 23:50 -0500, Nestor Camacho III wrote: > >> I am wondering if anyone has come into this really unique problem... >> >> Short story... >> >> I had a gateway box on different hardware, that finally kicked the >> bucket. I purchased new hardware rebuilt gentoo on it and I was able to >> get on the internet as I used to with the old box....however... with one >> issue that has gotten the best of me... I have spent hours recompiling >> kernel options and iptables. Google'ing and reading as much as I can on >> the issue. I have sniffed the traffic both on the gateway server and on >> the laptop(s) that I have experienced the issue on. >> >> Now, what the problem is...I vpn (over ssl, to a Juniper device) to my >> job. What I am seeing is when I finally connect I can ping hosts >> internal to my work network, but when I try to initiate a connection >> (ssh, http, rdp, etc) I get no where. It just hangs on trying to >> establish the connections. >> >> Upon sniffing the traffic I see that I start to generate duplicate >> acks/packets and the connection fails. >> >> I have tried already enableing and disabling things with ethtool to no >> avail. >> >> Now the kicker! I boot up on the same computer using Ubuntu live cd and >> import the same firewall rules and everything works as it should! >> >> It is an elusive issue and I know that I am not doing it justice in the >> email but any nod in the right direction would be greatly appreciated. >> >> Nes++ >> > > -- [email protected] mailing list
