Some miscellaneous notes I may split out into separate posts later... don't bookmark this one.
View open network connections on OS X
sudo lsof -lnP +M -i4
-l don't convert uids to login -n dont' convert network numbers to to hostnames -P don't convert port numbers to service names +M enable portmapping -i4 look for IPv4 connections
nettop. 3rd party apps include Little Snitch and RubberNet.
View open network connections on Linux
To start and monitor an new process:
strace -f -e trace=network -s 10000 PROCESS ARGUMENTS
To monitor an existing process with a known pid:
strace -p $PID -f -e trace=network -s 10000
To install an init.d script so it will run at startup time:
- copy script to /etc/rc.d/init.d
chkconfig (script) on
This will make symlinks in all of the runlevel directories to the init script. The script's runlevels should also be appropriate to your OS runlevel.
To see a linux context:
ls -lZ ps auxwwZ
To mark a file/directory as "safe":
restorecon -r dir
I was having trouble ssh'ing to an account: sshd seemed to be looking at
/root/.ssh/authorized_keys as it should, but wasn't finding anything there or telling me (in
/var/log/secure that something was wrong with the directory). I guessed that it had something to do with SELinux and lucked out this time.
Other things to try: in
selinux=0. From the command-line
setenforce 0 also works.
getenforce to show you the current setting.
/var/log/audit.log is typically where all SElinux messages go.
DNS zone transfer
To look at an entire DNS zone, you can do this:
dig (domain) @(ns) axfr
dig betterservers.com @ns1.betterservers.com axfr
Open file problem
I was having trouble opening files; I suspected I had hit my limit but wasn't familiar with how OS X handles open files.
To see what the limit is:
# ulimit -n 1024
Find the pid of the process having trouble:
# ps auxww | grep beanstalkd quapi 12077 0.1 0.0 7232 1704 ? Ss Dec04 16:16 /usr/local/bin/beanstalkd -l 127.0.0.1 -p 11300 -u quapi -b beanlog
See how many files this process has open:
# lsof -p 12077 | wc -l 25
See which processes are talking to it:
# netstat -atnlp | grep 11300 | grep -v beanstalkd tcp 0 0 127.0.0.1:37262 127.0.0.1:11300 ESTABLISHED 12156/perl tcp 0 0 127.0.0.1:37230 127.0.0.1:11300 ESTABLISHED 12128/perl tcp 0 0 127.0.0.1:37261 127.0.0.1:11300 ESTABLISHED 12154/perl tcp 0 0 127.0.0.1:37233 127.0.0.1:11300 ESTABLISHED 12134/perl tcp 0 0 127.0.0.1:37231 127.0.0.1:11300 ESTABLISHED 12136/perl tcp 0 0 127.0.0.1:37264 127.0.0.1:11300 ESTABLISHED 12150/perl tcp 0 0 127.0.0.1:37232 127.0.0.1:11300 ESTABLISHED 12132/perl tcp 0 0 127.0.0.1:37229 127.0.0.1:11300 ESTABLISHED 12130/perl tcp 0 0 127.0.0.1:37259 127.0.0.1:11300 ESTABLISHED 12152/perl tcp 0 0 127.0.0.1:37263 127.0.0.1:11300 ESTABLISHED 12158/perl
It turns out that I wasn't closing client connections in an event loop and so they just kept accumulating.
Increasing maxfiles on OS X Mavericks
Open or create
/etc/launchd.conf; add this line:
limit maxfiles 16384 16384
restart (still looking for a better way that restarting); there was a time when the hard limit could be "unlimited" but that is no longer true.
rpm installation from URL
rpm -iUvh https://...