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user ssh login troubleshooting issues


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Here I am going to keep updating ways to troubleshoot ssh login issues on linux or unix operating systems.  Even though there are several different flavors and types of linux, the basis is typically the same.  I am currently running/testing these commands on a RH 5.x system


SSH Login Records

$ cat /var/log/secure


SSH Login Attempts

$ cat /var/log/auth.log

(some helpful filters)

$ grep sshd.*Failed /var/log/auth.log | less

$ grep sshd.*Did /var/log/auth.log | less



permissions, compare files checksum


Failed Login Attempts

$ grep "authentication failure" /var/log/secure | awk '{ print $13 }' | cut -b7-  | sort | uniq -c


Capture login attempts

$ tcpdump -w xpackets.pcap src and port 22


$ tcpdump -D (shows available interfaces in the event you want to capture only on one interface with -i eth0)

$ tcpdump -r xpackets.pcap (will read the file file you just captured)

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