From: Mohamed Lrhazi (mohamed@your-site.com)
Date: Fri May 09 2003 - 09:20:09 EDT
Hello,
I traced a majordomo problem on a Solaris 9 server, running Postfix, to
an issue with connections to the loopback interface...
# uname -a
SunOS thebe 5.9 Generic_112233-02 sun4u sparc SUNW,Ultra-Enterprise
When I telnet to port 25 on the loopback interface, it just hangs there:
# telnet localhost 25
Trying 127.0.0.1...
lsof -i TCP shows the following info:
...
telnet 20389 root 4u IPv4 0x30003dadcf0 0t0 TCP
1.2.3.5:64635->127.0.0.1:25 (SYN_SENT)
...
smtpd 18396 postfix 7u IPv4 0x30026e3cc38 0t0 TCP
1.2.3.4:25 (LISTEN)
smtpd 18396 postfix 11u IPv4 0x300049db3c0 0t39
TCP 1.2.3.4:25->218.184.118.251:4321 (ESTABLISHED)
smtpd 19362 postfix 6u IPv4 0x300043f1558 0t0 TCP
127.0.0.1:25 (LISTEN)
smtpd 19362 postfix 7u IPv4 0x30026e3cc38 0t0
TCP 1.2.3.4:25 (LISTEN)
smtpd 19366 postfix 6u IPv4 0x300043f1558 0t0 TCP
127.0.0.1:25 (LISTEN)
smtpd 19366 postfix 7u IPv4 0x30026e3cc38 0t0
TCP 1.2.3.4:25 (LISTEN)
smtpd 19367 postfix 6u IPv4 0x300043f1558 0t0 TCP
127.0.0.1:25 (LISTEN)
smtpd 19367 postfix 7u IPv4 0x30026e3cc38 0t0
TCP 1.2.3.4:25 (LISTEN)
master 8265 root 12u IPv4 0x3009a6ef238 0t0 TCP
1.2.3.5:25 (LISTEN)
This machine has three IPs, replaced above with 1.2.3.4 on hme0 and a
virtual one, hme0:1 of 1.2.3.5, and one different net on hme1.
Notice that my telnet localhost appears to be coming from my virtual
interface!
Ooops, while writing the above, I thought I ll go and get a netstat -rn
to add to this email....
# netstat -rn
Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
1.2.3.0 1.2.3.5 U 1 1563 hme0:1
1.2.3.0 1.2.3.4 U 1 0 hme0
10.0.0.0 10.0.2.37 U 1 3545 hme1
224.0.0.0 1.2.3.4 U 1 0 hme0
default 1.2.3.1 UG 11178321
Yup, no route for 127.0.0.1!
ifconfig shows the loopback interface is fine, right netmask brodcast
and UP....
I reboot the system, everything comes back to normal... untill some time
later, when that route goes away again..
Any idea what can cause the loopback route to go away?
I also remember now, that while troubleshooting a mail issue on this
same system I found out the loopback interface was actually down,
ifconfig lo0 did not show the UP flag!! What could brign lo0 down?
Thank you very much, I will summerize.
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