Dear Johnny, Yes, I have tried much larger numbers than 60 and 3 for the above two parameters respectively. And I am sure it is using ‘protocol 2’ because it’s uncommented in sshd_config. Is there a way to catch what’s happing before quit? I couldn’t see anything except for the line ‘write failed, broken pipe’. Thanks. Hua At 2015-10-08 19:37:24, "Johnny Hughes" <johnny at centos.org> wrote: >On 10/07/2015 10:45 PM, Hua Wang wrote: >> >>> >>>> I tried to ping the server, and it can accept all data. Is there a good way >>>> to check it? >>> >>> ssh -v, ssh -vv and ssh -vvv might give you some interesting information. >>> >> Yes, I tried ssh -vvv. It gave a lot of information while login, but it quit without any further information except for “write failed, broken pipe’. >> >>>> The problem came out while reinstalling centos 7.7. >>> >>> Since you're apparently using some kind of an unofficial or non-standard version of Centos, you might want to try using a current (regular) one instead. >>> >> >> Sorry I made a mistake for the version. I am using v7 instead of v7.7. >> > >Try using ClientAliveMaxCount and ServerAliveCountMax (you can set them >to 5 or 8 instead of the default of 3 and also make the timeouts higher >than 60. > >make sure you are using 'protocol 2'. >