no buffer space available

[Dave [Hawk-Systems]]

experienced some failures to ftp into a server, either direct or over ssh.
Error as interpreted by the various ftp clients was no buffer space available,
or permission errors on trying to upload files.

noted the following in the logs;
May 16 12:28:50 server sshd[9057]: error: socket: No buffer space available
May 16 12:28:50 server sshd[9057]: error: connect 127.0.0.1 port 21: failed.
May 16 12:32:21 server sshd[9575]: error: socket: No buffer space available
May 16 12:32:21 server sshd[9575]: error: connect 127.0.0.1 port 21: failed.

netstat -m shows the following;
229/2544/6144 mbufs in use (current/peak/max):
        173 mbufs allocated to data
        56 mbufs allocated to packet headers
169/758/1536 mbuf clusters in use (current/peak/max)
2152 Kbytes allocated to network (46% of mb_map in use)
0 requests for memory denied
0 requests for memory delayed
0 calls to protocol drain routines

df -k shows space isn't a problem;
Filesystem  1K-blocks     Used    Avail Capacity  Mounted on
/dev/ad0s1a     99183    35632    55617    39%    /
/dev/ad0s1f  55177478  5717582 45045698    11%    /usr
/dev/ad0s1e     19815      522    17708     3%    /var
/dev/ad1s1e  56824822  6285343 45993494    12%    /backup
procfs              4        4        0   100%    /proc

any ideas, as currently we cannot currently ftp into this box

Dave