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Mar
13
awarded  Popular Question
Jan
4
comment ADSL router happily accepts IPv6 packets of 2K in size
It was the offloading feature at work - see my comment on your answer.
Jan
4
accepted ADSL router happily accepts IPv6 packets of 2K in size
Jan
4
comment ADSL router happily accepts IPv6 packets of 2K in size
YES! Your edit about TCP Segmentation Offloading (TSO) is spot on. I disabled TSO on my ethernet using ethtool -K eth0 tso off and no packets are sent that are larger than 1492. So as you said, wireshark wasn't showing the whole picture.
Jan
4
comment ADSL router happily accepts IPv6 packets of 2K in size
I embedded the exact sizes in the text.
Jan
4
revised ADSL router happily accepts IPv6 packets of 2K in size
Noted lack of packet monitoring.
Jan
4
comment ADSL router happily accepts IPv6 packets of 2K in size
If it's not link layer, and the sender doesn't retransmit smaller segments, then where is the frag happening? maybe over the PPP? (I need to find a way to monitor packet traffic on my router).
Jan
4
comment ADSL router happily accepts IPv6 packets of 2K in size
Superb detail! The use of smaller TCP segments over IP frag is now clear. I also had the MTU wrong when I wrote the question, it's actually 1492. So if I understand correctly, the router's free to do its own frag at link layer, and that's fine. But if that's the case, why do I get "Packet too big" messages in the first place? It's also the case that the subsequent >2K packets actually go through without a problem (ie they're not retransmitted as two smaller ones).
Jan
4
awarded  Yearling
Jan
4
revised ADSL router happily accepts IPv6 packets of 2K in size
Corrected the MTU of the ADSL
Jan
4
comment ADSL router happily accepts IPv6 packets of 2K in size
It's actually Shibby's fork, and I updated it last 3 weeks ago. However, even if it was old and unmaintained, I'd expect less from it. Right now, it's doing magic (obviously I'm missing something), passing packets larger than its MTU!
Jan
4
asked ADSL router happily accepts IPv6 packets of 2K in size
Nov
26
awarded  Caucus
Aug
10
revised Drop packets after NAT in iptables
Added more details.
Aug
10
comment Drop packets after NAT in iptables
I see. I'd simplified my question. I'm actually trying to rate limit a specific IP (using hashlimit), so not all packets are dropped.
Aug
10
comment Drop packets after NAT in iptables
I've tried adding a rule to FORWARD chain in filter table (ie -I FORWARD 1 -d 192.0.0.0/24 -j DROP). Without -d, I achieve filtering, but as I understand it, both directions are filtered. I only want packets destined for the NAT clients to be filtered.
Aug
10
asked Drop packets after NAT in iptables
Aug
2
awarded  Popular Question
Jul
2
awarded  Curious
Oct
10
awarded  Popular Question