[tor-relays] inet_csk_bind_conflict

lists at for-privacy.net lists at for-privacy.net
Thu Dec 15 22:25:28 UTC 2022


On Freitag, 2. Dezember 2022 16:30:48 CET Chris wrote:

> As I'm sure you've already gathered, your system is maxing out trying to
> deal with all the connection requests. When inet_csk_get_port is called
> and the port is found to be occupied then inet_csk_bind_conflict is
> called to resolve the conflict. So in normal circumstances you shouldn't
> see it in perf top much less at 79%. There are two ways to deal with it,
> and each method should be complimented by the other. One way is to try
> to increase the number of ports and reduce the wait time which you have
> somehow tried. I would add the following:

I use on old Dual Intel Xeon E5-2680v2 CPU's, 256 GB RAM & the Tor IP's/traffic 
routed over a dual 10G NIC. (40 exit relays)

> net.ipv4.tcp_fin_timeout = 20
net.ipv4.tcp_fin_timeout = 4

> net.ipv4.tcp_max_tw_buckets = 1200
net.ipv4.tcp_max_tw_buckets = 2000000

> net.ipv4.tcp_keepalive_time = 1200
net.ipv4.tcp_keepalive_time = 60

> net.ipv4.tcp_max_syn_backlog = 8192
net.core.netdev_max_backlog = 262144

https://github.com/boldsuck/tor-relay-configs/blob/main/etc/sysctl.d/local.conf

> 
> The complimentary method to the above is to lower the number of
> connection requests by removing the frivolous connection requests out of
> the equation using a few iptables rules.
> 
> I'm assuming the increased load you're experiencing is due to the
> current DDos attacks and I'm not sure if you're using anything to
> mitigate that but you should consider it.
> 
> You may find something useful at the following  links
> 
> [1](https://github.com/Enkidu-6/tor-ddos)
> 
> [2](https://github.com/toralf/torutils)
> 
> [background](https://gitlab.torproject.org/tpo/community/support/-/issues/40
> 093)
> 
> Cheers.
> 
> On 12/1/2022 3:35 PM, Christopher Sheats wrote:
> > Hello tor-relays,
> > 
> > We are using Ubuntu server currently for our exit relays.
> > Occasionally, exit throughput will drop from ~4Gbps down to ~200Mbps
> > and the only observable data point that we have is a significant
> > increase in inet_csk_bind_conflict, as seen via 'perf top', where it
> > will hit 85% [kernel] utilization.
> > 
> > A while back we thought we solved with with two /etc/sysctl.conf settings:
> > net.ipv4.ip_local_port_range = 1024 65535
> > net.ipv4.tcp_tw_reuse = 1
> > 
> > However we are still experiencing this problem.
> > 
> > Both of our (currently, two) relay servers suffer from the same
> > problem, at the same time. They are AMD Epyc 7402P bare-metal servers
> > each with 96GB RAM, each has 20 exit relays on them. This issue
> > persists after upgrading to 0.4.7.11.
> > 
> > Screenshots of perf top are shared
> > here: https://digitalcourage.social/@EmeraldOnion/109440197076214023
> > 
> > Does anyone have experience troubleshooting and/or fixing this problem?


-- 
╰_╯ Ciao Marco!

Debian GNU/Linux

It's free software and it gives you freedom!
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