Messages in this thread | | | Date | Thu, 07 Apr 2005 19:33:09 +0200 | From | Florian Attenberger <> | Subject | Re: PMTU, MSS and "fragmentation needed" problem with linux? |
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from my shorewall.conf. ----------------- # # MSS CLAMPING # # Set this variable to "Yes" or "yes" if you want the TCP "Clamp MSS to PMTU" # option. This option is most commonly required when your internet # interface is some variant of PPP (PPTP or PPPoE). Your kernel must # have CONFIG_IP_NF_TARGET_TCPMSS set. # # [From the kernel help: # # This option adds a `TCPMSS' target, which allows you to alter the # MSS value of TCP SYN packets, to control the maximum size for that # connection (usually limiting it to your outgoing interface's MTU # minus 40). # # This 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. # ] # # If left blank, or set to "No" or "no", the option is not enabled. # CLAMPMSS=1412 --------------------
see also: http://en.tldp.org/HOWTO/IP-Masquerade-HOWTO/mtu-issues.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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