Linux Server FTP, telnet, ssh slow

Environment

[Netcool @ inmsc4 ~] $ Uname-
Linux inmsc4 2.6.18-194. EL5 #1 SMP Tue Mar 16 21:52:39 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux
[Netcool @ inmsc4 ~] $

Dual-nic

Symptom description

SSH and FTP are both normal. One day, it suddenly slowed down. However, after logon, the operation is not slow and normal.

According to Baidu, it is related to reverse DNS resolution. This statement is half correct because the server suddenly slows down.

Therefore, check the two NICs,

[Root @ inmsc4 ~] # Route
Kernel IP routing table
Destination gateway genmask flags metric ref use iface
192.168.1.0*255.255.255.0 u 1 0 0 eth4
192.168.1.0*255.255.255.0 u 1 0 0 eth5
Default 192.168.1.1 0.0.0.0 ug 0 0 0 eth4

After executing the route command, the last line waited for a long time.

Ping the IP address of eth4 with severe packet loss.

Solution

It may be that the network card of eth4 is broken, the network cable is virtual, and the switch port is faulty .....

[Root @ inmsc4 ~] # Ifdown eth4

[Root @ inmsc4 ~] # Route
Kernel IP routing table
Destination gateway genmask flags metric ref use iface
192.168.1.0*255.255.255.0 u 1 0 0 eth5
Default 192.168.1.1 0.0.0.0 ug 0 0 0 eth5

Now, eth5 is working properly.

Reference URL:

Http://linux.sheup.com/linux/linux3708.htm

Http://hi.baidu.com/misaiya2008/item/448de71e922872731009b5dc

Http://doc.linuxpk.com/3887.html