Date: Wed, 18 May 2016 20:28:58 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: Grzegorz Junka <list1@gjunka.com>, freebsd-jail@freebsd.org Subject: Re: netstat -rn in jail doesn't work Message-ID: <573CB46A.6040308@quip.cz> In-Reply-To: <87302b92-dcae-0ed2-92e2-0c29779c0fd3@gjunka.com> References: <87302b92-dcae-0ed2-92e2-0c29779c0fd3@gjunka.com>
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Grzegorz Junka wrote on 05/18/2016 18:37:
> What may be the reason that netstat -rn works in one jail and doesn't in
> another?
>
> root@app2:/ # netstat -rn
> Routing tables
>
> Internet:
> Destination Gateway Flags Netif Expire
> 192.168.1.76 link#4 UHS lo0
>
>
> root@pjp1:/ # netstat -rn
> netstat: kvm not available: /dev/mem: No such file or directory
> Routing tables
> rt_tables: symbol not in namelist
I don't know the reason but I can confirm this behavior. I know about
this for a long time. Netstat complains about /dev/mem for some other
params too even if it outputs correct values for example for opened tcp
connections:
/# netstat -s -p tcp
netstat: kvm not available: /dev/mem: No such file or directory
tcp:
1517892073 packets sent
1453939900 data packets (2274781047202 bytes)
759536 data packets (929141944 bytes) retransmitted
59175 data packets unnecessarily retransmitted
0 resends initiated by MTU discovery
51907865 ack-only packets (26667901 delayed)
0 URG only packets
267 window probe packets
795506 window update packets
10493883 control packets
1487401217 packets received
1417951529 acks (for 2273802396874 bytes)
7502860 duplicate acks
38600 acks for unsent data
1368386110 packets (2153255668968 bytes) received
in-sequence
222423 completely duplicate packets (39239815 bytes)
11980 old duplicate packets
221 packets with some dup. data (94160 bytes duped)
35171 out-of-order packets (15770219 bytes)
21 packets (11 bytes) of data after window
11 window probes
1863690 window update packets
1642030 packets received after close
281 discarded for bad checksums
0 discarded for bad header offset fields
0 discarded because packet too short
87 discarded due to memory problems
2448384 connection requests
7800552 connection accepts
0 bad connection attempts
109 listen queue overflows
339306 ignored RSTs in the windows
10221160 connections established (including accepts)
10554092 connections closed (including 1990441 drops)
5674590 connections updated cached RTT on close
5677848 connections updated cached RTT variance on close
1583021 connections updated cached ssthresh on close
10125 embryonic connections dropped
1405786035 segments updated rtt (of 1374995187 attempts)
404689 retransmit timeouts
1681 connections dropped by rexmit timeout
608 persist timeouts
0 connections dropped by persist timeout
0 Connections (fin_wait_2) dropped because of timeout
12388 keepalive timeouts
11896 keepalive probes sent
492 connections dropped by keepalive
38184853 correct ACK header predictions
46419366 correct data packet header predictions
7826351 syncache entries added
45759 retransmitted
55797 dupsyn
84 dropped
7800552 completed
40 bucket overflow
0 cache overflow
19220 reset
7941 stale
109 aborted
0 badack
230 unreach
0 zone failures
7826435 cookies sent
1784 cookies received
212203 hostcache entries added
28 bucket overflow
104273 SACK recovery episodes
242234 segment rexmits in SACK recovery episodes
303575028 byte rexmits in SACK recovery episodes
1538523 SACK options (SACK blocks) received
12421 SACK options (SACK blocks) sent
114 SACK scoreboard overflow
0 packets with ECN CE bit set
0 packets with ECN ECT(0) bit set
0 packets with ECN ECT(1) bit set
0 successful ECN handshakes
0 times ECN reduced the congestion window
0 packets with valid tcp-md5 signature received
0 packets with invalid tcp-md5 signature received
0 packets with tcp-md5 signature mismatch
0 packets with unexpected tcp-md5 signature received
0 packets without expected tcp-md5 signature received
I tried netstat -rn in all 8 jails on our test machine. 4 of them works,
the other 4 don't work.
netstat -rn doesn't work in those jail which are older than host environment
netstat -s -p tcp prints error message even in the newest jails:
netstat: kvm not available: /dev/mem: No such file or directory
Miroslav Lachman
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