Am 06.09.2009 19:47, schrieb Marek Lindner:
When using the
tunneling interface, the MTU is set to a lower value then
1500 bytes (1431 bytes). B.A.T.M.A.N have in addition to the NAT-Helper
set the TCPMSS Flag to something like 1371 bytes (1431 bytes - 20 Bytes
of MAC-Address and - 40 Bytes of TCP/IP Header). I found nothing about
TCPMSS on my firewall-rules (iptables) in the table "mangle".
Without TCPMSS, packages that transport more then 1371 bytes will be
silently dropped in my case.
Not sure how you get to these numbers (1431 / 1371) as the batman tunnel is
running over UDP which costs 29 Bytes [20 Bytes IP + 8 Bytes UDP + 1 Byte
batman stuff] in total, reducing the maximum packet size to 1471.
You are right about the the TCPMSS configuration - batman could set this
automatically as well. I suggest something like this:
iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -o gate0 -j TCPMSS --clamp-
I got these numbers by "/sbin/ip addr show dev gate0".
gate0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1431 qdisc
pfifo_fast qlen 500
inet 169.254.0.0/32 scope global gate0
MTU is set to 1431 bytes.
have my own policy-routing-script, because B.A.T.M.A.N does
not support HOST-Routes xxx.205.12.4/32. But why does B.A.T.M.A.N not
fully support Host-Routes? A mash with only Host-Addresses is easier to
administrate then complete networks. A second goal is, that the ad-hoc
mobile user is free to change his position across the net.
Your own policy-routing-script ?
Why do you think batman does not support host routes ? I had the feeling
batman supports host routes in all possible ways. :-)
IP-Host #1: 22.214.171.124 / 32
IP-Host #2: 126.96.36.199 / 32
IP RULES ON "HOST #2":
~ $ /sbin/ip rule show
6600: to 188.8.131.52 lookup batman_hosts 
6601: from all lookup batman_networks 
6700: to 184.108.40.206 lookup batman_unreach 
Host #1 (220.127.116.11) is in the routingtable of batman_hosts .
But i can not ping 18.104.22.168, because the kernel will not enter the
When i configure my Host #2 to a /24 network, all went fine. Then the
rule will setuped as follow:
6600: to 22.214.171.124/24 lookup batman_hosts 
In this case, i had to write my own routing-policy-script.