Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

30 minutes ago my router is not accepting ssh connection. Well, ports is open (due to nmap), ssh simply hangs on reading from Cisco socket (observation from strace):

/home/rafal/.ssh/id_dsa-cert type -1
) = 60
open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 4
_llseek(4, 0, [0], SEEK_CUR)            = 0
fstat64(4, {st_mode=S_IFREG|0644, st_size=2871, ...}) = 0
mmap2(NULL, 2871, PROT_READ, MAP_SHARED, 4, 0) = 0xb78cb000
_llseek(4, 2871, [2871], SEEK_SET)      = 0
munmap(0xb78cb000, 2871)                = 0
close(4)                                = 0
open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 4
_llseek(4, 0, [0], SEEK_CUR)            = 0
fstat64(4, {st_mode=S_IFREG|0644, st_size=2871, ...}) = 0
mmap2(NULL, 2871, PROT_READ, MAP_SHARED, 4, 0) = 0xb78cb000
_llseek(4, 2871, [2871], SEEK_SET)      = 0
munmap(0xb78cb000, 2871)                = 0
close(4)                                = 0
rt_sigaction(SIGPIPE, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPIPE, {SIG_IGN, [], 0}, NULL, 8) = 0
read(3, 

Where 3 is file descripor of connection with router (ESTABLISHED state, due to the netstat).

tcp        0      0 192.168.80.50:38954     192.168.81.1:22         ESTABLISHED 24839/ssh       

One hour ago I was still able to connect. Now there is no more access trough the console port - what I should do?

share|improve this question
    
...when you say you do not have access through the console port you mean the actual physical console port on the router? or are you referring to the ssh connection? if your router was accepting connections before and now these are getting stuck, it may be related to the router's CPU usage...thing is that if you do not have access to the physical console port you will not be able to do much troubleshooting sans reboot the device... –  jliendo Apr 6 '11 at 18:53
    
Have you restarted the device? –  evolvd Apr 11 '11 at 15:52

1 Answer 1

up vote 1 down vote accepted

So no SSH access, and no console access? I'm assuming telnet is not available?

Do you have access via SNMP (read/write community)? You could enable telnet via SNMP commands and see if that gets you in to the box?

You can use SNMP to execute other commands - but ultimately it sounds like you've hit something that is going to require a reload of the router. Either issue reload via SNMP access, or power cycle the box physically.

Edit: Other thoughts - if you get access to the box via Telnet or SNMP, you can "crypto key generate RSA" to re-generate your crypto keys. This may recycle the SSHD process on the router. Whatever you do, make sure you get a copy of the running-config before you reboot, or at least issue a copy run start to save any changes that were made to the box.

share|improve this answer
    
I don't know what was the problem - I think high CPU usage. After 30 mintues it started to work... –  bluszcz Apr 13 '11 at 10:56

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.