qMp (Quick Mesh Project) - Packages

Linux ip stack sends a ICMP Code 3 Type 4 (Fragmentation Needed) packet when one package exceeds the MTU (e.g. the MTU of bmx6 tunnels) and this package has DF (Don't Fragmentation) flag (e.g. SSL-encrypted WWW sites).

Some ISPs block this ICMP Code 3 Type 4 (Fragmentation Needed) packages, then too big packages with DF (Don't Fragmentation) flag sent by servers never reach to clients. We need to change MSS value in TCP negotiation time.

See also http://www.tldp.org/HOWTO/IP-Masquerade-HOWTO/mtu-issues.html