mirror of
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86 lines
3.3 KiB
Plaintext
86 lines
3.3 KiB
Plaintext
Most operating systems limit an amount of TCP sockets that can be used
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simultaneously. It is possible for a busy Tor relay to run into these
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limits, thus being unable to fully utilize the bandwidth resources it
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has at its disposal. Following system-specific tips might be helpful
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to alleviate the aforementioned problem.
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Linux
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-----
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Use 'ulimit -n' to raise an allowed number of file descriptors to be
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opened on your host at the same time.
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FreeBSD
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-------
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Tune the followind sysctl(8) variables:
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* kern.maxfiles - maximum allowed file descriptors (for entire system)
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* kern.maxfilesperproc - maximum file descriptors one process is allowed
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to use
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* kern.ipc.maxsockets - overall maximum numbers of sockets for entire
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system
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* kern.ipc.somaxconn - size of listen queue for incoming TCP connections
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for entire system
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See also:
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* https://www.freebsd.org/doc/handbook/configtuning-kernel-limits.html
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* https://wiki.freebsd.org/NetworkPerformanceTuning
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Mac OS X
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--------
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Since Mac OS X is BSD-based system, most of the above hold for OS X as well.
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However, launchd(8) is known to modify kern.maxfiles and kern.maxfilesperproc
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when it launches tor service (see launchd.plist(5) manpage). Also,
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kern.ipc.maxsockets is determined dynamically by the system and thus is
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read-only on OS X.
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OpenBSD
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-------
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Because OpenBSD is primarily focused on security and stability, it uses default
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resource limits stricter than those of more popular Unix-like operating systems.
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OpenBSD stores a kernel-level file descriptor limit in the sysctl variable
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kern.maxfiles. It defaults to 7,030. To change it to, for example, 16,000 while
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the system is running, use the command 'sudo sysctl kern.maxfiles=16000'.
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kern.maxfiles will reset to the default value upon system reboot unless you also
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add 'kern.maxfiles=16000' to the file /etc/sysctl.conf.
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There are stricter resource limits set on user classes, which are stored in
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/etc/login.conf. This config file also allows limit sets for daemons started
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with scripts in the /etc/rc.d directory, which presumably includes Tor.
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To increase the file descriptor limit from its default of 1,024, add the
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following to /etc/login.conf:
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tor:\
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:openfiles-max=13500:\
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:tc=daemon:
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Upon restarting Tor, it will be able to open up to 13,500 file descriptors.
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This will work *only* if you are starting Tor with the script /etc/rc.d/tor. If
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you're using a custom build instead of the package, you can easily copy the rc.d
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script from the Tor port directory. Alternatively, you can ensure that the Tor's
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daemon user has its own user class and make a /etc/login.conf entry for it.
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High-bandwidth relays sometimes give the syslog warning:
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/bsd: WARNING: mclpools limit reached; increase kern.maxclusters
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In this case, increase kern.maxclusters with the sysctl command and in the file
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/etc/sysctl.conf, as described with kern.maxfiles above. Use 'sysctl
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kern.maxclusters' to query the current value. Increasing by about 15% per day
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until the error no longer appears is a good guideline.
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Disclaimer
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----------
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Do note that this document is a draft and above information may be
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technically incorrect and/or incomplete. If so, please open a ticket
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on https://gitlab.torproject.org or post to tor-relays mailing list.
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Are you running a busy Tor relay? Let us know how you are solving
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the out-of-sockets problem on your system.
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